To provide a connector for restraining increase of the number of components, simplifying its structure, improving assembling operability, and reducing size and cost, for providing a half-insertion-coupling detection structure.

An insertion-coupling checking part 3 has three configurations. The first one is structured of a convex part 12 formed at a finger pushing part 8 of a lock arm 5, and a hole part 13 formed at an upper part 10 of a housing lock protection part 6. The second one is structured of an arm side collision surface 14 formed around the convex part 12, and a protection side collision surface 15 formed at an underside of the upper part 10. The third one is structured of an insertion-coupling check line 16 formed at a back part of the finger pushing part 8, and an insertion-coupling check line 17 formed at a back part of the housing lock protection part 6.