Composition for forming protective film including specific crosslinking agent, and pattern formation method in which same is used

A composition for forming a protective film against basic aqueous hydrogen peroxide solution, comprising a crosslinker having, in one molecule, two or more groups that are at least one selected from the group consisting of a glycidyl group, a terminal epoxy group, an epoxycyclopentyl group, an epoxycyclohexyl group, an oxetanyl group, a vinyl ether group, an isocyanate group, and a blocked isocyanate, a compound having a group of the following Formula (1):

• (wherein X1 is a substituent reacting with the crosslinker, R0 is a direct bond or a C1-2 alkylene group, X2 is a C1-2 alkyl group, a C1-2 alkoxy group, or fluoro group, a is an integer of 0 to 2, b is an integer of 1 to 3, when b is 2 or 3, groups of —R0—X1 are optionally different from each other, c is an integer of 0 to 4, when c is 2, 3, or 4, the groups of X2 are optionally different from each other, and b and c satisfy a relational expression of 1≤(b+c)≤5) on a side chain or a terminal and having a weight average molecular weight of 800 or more, and an organic solvent.