content_image/899267.jpg content_image/899276.jpg content_image/899266.jpg
described above for the substituent which the polycyclic aliphatic hydrocarbon structure may have. 

The position of substitution of -O-Y-X$_{2 }$ in the gen› eral formula ( 4) may be the para-position, the meta-position, or the ortho-position with respect to the bonding position of a benzene ring to a polymer main chain, but, and the para-position is preferred. 

In the present invention, the repeating unit represented by the general formula (3) described above is most preferably a repeating unit represented by the following general for› mula (4’). 

[Chem. 28] 

In the general formula (4’), R$_{13 }$ represents a hydrogen atom or a methyl group. 

In the general formula (4’), R$_{13 }$ represents a hydrogen atom or a methyl group, but a hydrogen atom is particularly preferred. 

The position of substitution of an adamantyl ester group 35 in the general formula (4’) may be the para-position, the meta-position, or the ortho-position with respect to the bonding position of a benzene ring to a polymer main chain, but, and the para-position is preferred. 40 

Specific examples of the repeating unit shown by the general formula (3) include the following. 

<img src='content_image/899267.jpg'>

<img src='content_image/899276.jpg'>

(4’) 

[Chem. 29] 

<img src='content_image/899266.jpg'>

-continued 

