A lever-type connector, comprising: a main body side housing to which a mating side connector is connectable from a front end surface toward a rear end surface of the main body side housing and which is formed with a lever accommodation space extending in a direction perpendicular to a connecting direction, in which the mating side connector is connected, and forming an opening on a side end surface; a slide lever which is a long plate-like member, inserted into the lever accommodation space through the opening with one longitudinal end thereof as a leading end part in the lead and arranged to be movable back and forth along an extending direction of the lever accommodation space; wherein: the slide lever includes a cam groove engageable with a cam pin projecting on the mating side connector; the cam groove includes an open end portion open on an end surface of the slide lever extending in an inserting direction of the slide lever, and a path part extending from the open end portion to a deepest portion of the cam groove; the path part includes a first path part connected to the open end portion and extending toward the leading end part with distance from the end surface, and a second path part extending away from the leading end part with distance from the end surface and connected to the deepest portion, characterized in that the slide lever further includes a return preventing portion (43; 43a) configured to prevent, by coming into contact with the cam pin, the cam pin from moving back from the second path part to the first path part and configured to allow the cam pin to enter the second path part from the first path part. a main body side housing to which a mating side connector is connectable from a front end surface toward a rear end surface of the main body side housing and which is formed with a lever accommodation space extending in a direction perpendicular to a connecting direction, in which the mating side connector is connected, and forming an opening on a side end surface; a slide lever which is a long plate-like member, inserted into the lever accommodation space through the opening with one longitudinal end thereof as a leading end part in the lead and arranged to be movable back and forth along an extending direction of the lever accommodation space; the slide lever includes a cam groove engageable with a cam pin projecting on the mating side connector; the cam groove includes an open end portion open on an end surface of the slide lever extending in an inserting direction of the slide lever, and a path part extending from the open end portion to a deepest portion of the cam groove; the path part includes a first path part connected to the open end portion and extending toward the leading end part with distance from the end surface, and a second path part extending away from the leading end part with distance from the end surface and connected to the deepest portion, characterized in that the slide lever further includes a return preventing portion (43; 43a) configured to prevent, by coming into contact with the cam pin, the cam pin from moving back from the second path part to the first path part and configured to allow the cam pin to enter the second path part from the first path part.