A connector, which can prevent an unprepared release and ensure safety without a projecting portion (a portion which projects), is provided. A connector includes a connector housing to which a hose is connected; a male member mounted on the connector housing; and a lock member which can engage and disengage between the connector housing and the male member. The connector housing includes a lock-member guide wall guiding the lock member; an engagement projection engaging with one portion of the lock member, and restricting the lock member from descending; a sliding surface where a tip portion slides accompanied by a movement of the lock member; and a through-hole through which one portion of the lock member held by the lock-member guide wall passes, and which is formed to engage with an engagement portion formed on an outer periphery of the male member mounted on the connector housing. In the lock member, the movement is restricted by the engagement projection, and after an engagement with the engagement projection is released, the lock member descends and is removed from the engagement portion so as to prevent an unprepared release and ensure safety, and to eliminate a projecting portion.