A lock mechanism includes a hood (20) that is arranged so as to surround the periphery of a male member (10) and is for insertion of a female connector (100), and a single lock lever (30) having a cantilever support structure capable of elastic displacement. The lock lever (30) includes a claw (34) for engaging with the female connector (100), and an operation portion (35) for elastically displacing the lock lever (30) in a direction of separation from the male member (10). The claw (34) and the operation portion (35) are provided on the free end side of the lock lever (30).