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) is arranged with the free end (30a) thereof on the tip side of the male member (10), with the fixed end (30b) thereof on the base end side of the male member (10), and with the lengthwise direction thereof being approximately parallel to the male member (10). The lock lever (30) includes a claw (34) for engaging with the female connector (100). An operation arm (35) protrudes from the face of the lock lever (30) on the side opposite to the male member (10), and extends toward the fixed end (30b) side. If a pressing force in the direction approaching the male member (10) is applied to the tip (35a) of the operation arm (35), the lock lever (30) undergoes elastic deformation such that the claw (34) moves away from the male member (10).
