Provided is a crosslinkable composition for use in a member of an air management system for an ammonia combustion engine, the composition containing a fluoroelastomer and a cross-linking agent, and further containing hydrotalcite as an acid acceptor, or containing or not containing an acid acceptor other than hydrotalcite as an acid acceptor, wherein the content of the acid acceptor other than hydrotalcite is 0 parts by mass or more and less than 1 part by mass based on 100 parts by mass of the fluoroelastomer.