A negative photosensitive composition including an epoxy group-containing resin (A) and a cation polymerization initiator (B), the cation polymerization initiator (B) including at least one cation polymerization initiator (B0) selected from the group consisting of a compound represented by formula (b0-1) and a compound represented by formula (b0-2), and a cation polymerization initiator (B1) which generates an acid having a pKa of -3 or more (in the formulae, R<SP>b01</SP> to R<SP>b04</SP> each independently represents a fluorine atom or an aryl group which may have a substituent; R<SP>b05</SP> represents a fluorine atom or a fluorinated alkyl group which may have a substituent, provided that the plurality of R<SP>b05</SP> may be the same or different; q represents an integer of 1 or more; and each Q<SP>q+</SP> independently represents an organic cation having a valency of q).
Negative photosensitive composition, method of forming pattern