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structure having 3 to 10 ring members together with a carbon atom to which these are bonded. 

[0265] In Formula (ql), R$_{1 }$ represents a hydrogen atom or an organic group having 1 to 20 carbon atoms. 

[0266] Examples of the organic group having 1 to 20 carbon atoms represented by R$_{1 }$ in Formula (ql) include a chain hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, a heterocyclic group having 3 to 10 ring members, an epoxy group, a cyano group, a carboxy group, or a group repre› sented by -R’-Q-R". Here, R’ is a single bond or a hydro› carbon group having 1 to 20 carbon atoms. R" is a hydro› carbon group having 1 to 20 carbon atoms which may be substituted or a heterocyclic group having 3 to 10 ring members. Q is -0-, -CO-, -NH-, -SO$_{2}$ -, -SO-, or a group obtained by combining these. A portion or all of the hydrogen atoms that are included in the chain hydrocarbon group, the alicyclic hydrocarbon group, and the aromatic hydrocarbon group may be substituted with, for example, a halogen atom such as a fluorine atom or a substituent such as a cyano group, a carboxy group, a hydroxyl group, a thiol group, or a trialkylsilyl group. 

[0267] In Formula (ql), R$_{1 }$ is preferably a hydrogen atom in view of the copolymerizability of a monomer providing a repeating unit in which a lactone structure is directly con› nected to a main chain. 

[0268] In Formula (ql), R$_{2 }$ to Rs each independently represent a hydrogen atom, a fluorine atom, a hydroxyl group, or an organic group having 1 to 20 carbon atoms. 

[0269] Specific examples and suitable aspects of the organic group having 1 to 20 carbon atoms represented by R$_{2 }$ to Rs in Formula (ql) are the same as the organic group having 1 to 20 carbon atoms represented by R$_{1 }$ in Formula (ql). 

[0270] In Formula (ql), R$_{2 }$ and R$_{3}$ , and R$_{4 }$ and Rs may be bonded to each other to form a ring structure having 3 to 10 ring members together with carbon atoms to which these are bonded. 

[0271] Examples of the ring structure having 3 to 10 ring members which is formed by bonding R$_{2 }$ and R$_{3}$ , and R$_{4 }$ and Rs to each other, together with carbon atoms to which these are bonded include an alicyclic structure having an alicyclic ring such as include cyclopropane, cyclopentane, cyclo› hexane, norbornane, or adamantane; and a heterocyclic structure having a ring including a hetero atom. 

[0272] Examples of the heterocyclic structure having a ring including a hetero atom include a heterocyclic structure having a cyclic ether, a lactone ring, or a sultone ring, and other specific examples thereof include a heterocyclic struc› ture having an oxygen atom-containing ring such as tetra› hydrofuran, tetrahydropyran, y-butyrolactone, 1\-valerolac› tone, oxolane, and dioxane; and a heterocyclic structure having a sulfur atom-containing ring such as tetrahydroth› iophene, tetrahydrothiopyran, tetrahydrothiophene-1, I-di› oxide, tetrahydrothiopyran-1, I-dioxide, cyclopentanethione, and cyclohexanethione; and a heterocyclic structure having a nitrogen atom-containing ring such as piperidine. 

[0273] Among these, an alicyclic structure having cyclo› pentane, cyclohexane, or adamantane, and a heterocyclic structure having cyclic ether, a lactone ring, or a sultone ring is preferable. 

[0274] Here, the "ring structure" in the ring structure having 3 to 10 ring members which may be formed by 

bonding R$_{2 }$ and R$_{3}$ , and R$_{4 }$ and Rs to each other together with carbon atoms to which these are bonded refers to a structure containing a ring, and may be formed only from a ring or may be formed from a ring and another group such as a substituent. The bonding in a case where R$_{2 }$ and R$_{3}$ , and R$_{4 }$ and Rs are bonded to each other is not limited to a bonding by the chemical reaction. 

[0275] In Formula (ql), a represents an integer of 1 to 6. a is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1. 

[0276] In Formula ( q 1 ), in a case where a is 2 or more, the plurality of R$_{2}$ ’s and R/s may be identical to or different from each other. 

[0277] R$_{2 }$ and R$_{3 }$ each are preferably a hydrogen atom or a chain hydrocarbon group having 1 to 20 carbon atoms and more preferably a hydrogen atom. 

[0278] R$_{4 }$ and Rs each are preferably a hydrogen atom, a chain hydrocarbon group having 1 to 20 carbon atoms, a heterocyclic group having 3 to 10 ring members, or a group that forms a ring structure having 3 to 10 ring members by bonding these to each other together with carbon atoms to which these are bonded. 

[0279] Examples of the repeating unit represented by Formula (ql) include repeating units represented by the following formula, but the present invention is not limited to these. R$_{1 }$ in the following formula has the same meaning as R$_{1 }$ in Formula (ql). 

<img src='content_image/932035.jpg'>

[0280] A repeating unit obtained by directly connecting the lactone structure represented by Formula (ql) to a main chain may be used singly or two or more kinds thereof may be used in combination. 

[0281] With respect to all repeating units of the resin (A), the content of the repeating unit obtained by directly con› necting a lactone structure represented by Formula (ql) to a main chain is not particularly limited, but is preferably 5 to 60 mo! %, more preferably 5 to 50 mo! %, and even more preferably 10 to 40 mo! %. 

[0282] The resin (A) may include another repeating unit. 

[0283] For example, the resin (A) may include a repeating unit having a hydroxyl group or a cyano group. Examples of the repeating unit include repeating units disclosed in para› graphs <0081> to <0084> of JP2014-098921A. 

## Other Repeating Units 

