A spring lock type connector has a male connector (M) with a front receptacle (52). A female connector (F) is fit on an outer peripheral side of the front receptacle (52) and has a terminal accommodating portion (12) to be fit into the front receptacle (52). A spring (40) is mounted onto the female connector (F) and deforms to spread as the female connector (F) is connected to the male connector (M). The connectors are locked in a properly connected state by a spring force of the spring. Engaging recesses (54) are provided on the outer surface of the male connector (M) and engage with the spring (40). The recesses (54) are recessed inwardly of the outer surface of the front receptacle (52) and are more backward than a connecting bottom surface (53) on a back end of the inner surface of the front receptacle (52).