Locking mechanism and connector set

A locking mechanism with which it is possible to ensure sufficient locking strength without compromising workability of a mating operation and a removal operation for a mating unit (for example, a connector set) comprising a first structure and a second structure, and a connector set are provided. The locking mechanism, which is configured to maintain a mated state of the first structure and the second structure with which the first structure can be mated, comprises: an engaging portion provided on the first structure; an engaged portion provided on the second structure and structurally engageable with the engaging portion; and an urging portion that urges and maintains the engaging portion in a normal state in which the engaging portion engages the engaged portion. The engaging portion is configured to be able to translate along a side surface of the first structure against the urging force of the urging portion so as to disengage from the engaged portion.