Negative photosensitive resin composition, pattern formation method, and laminated film

A negative photosensitive resin composition comprising:

• an epoxy group-containing resin (A);
• and
• a cationic polymerization initiator (I),
• wherein the cationic polymerization initiator (I) includes a sulfonium salt (I0) represented by General Formula (I0),
• wherein in Formula (I0), R1 represents a thioxanthonyl group;
• R2 represents an aryl group having 6 to 30 carbon atoms, in which a part of hydrogen atoms in the aryl group is substituted with a substituent (t), the substituent (t) being at least one selected from the group consisting of an alkyl group having 1 to 18 carbon atoms or an alkoxy group having 1 to 18 carbon atoms, R3 to R5 are each an alkyl group or an alkoxy group, k, m, and n represent the numbers of R3, R4, and RS, in which k is an integer of 0 to 4, m is an integer of 0 to 3, and n is an integer of 1 to 4, in a case where each of k, m, and n is 2 or more, a plurality of R3's, R4's, or R5's may be the same or different from each other, A is a group represented by —S—, —O—, —SO—, —SO2—, or —CO—, O is an oxygen atom, S is a sulfur atom, and X− represents a monovalent polyatomic anion.