A connector mateable with and removable from a mating connector along an up-down direction, the connector being attached with a cover when used, wherein: the mating connector comprises a cam shaft; the connector comprises a housing, a lever and a slider; the lever is configured to be attached to the housing to be rotatable between a first position and a second position in a state before the cover is attached to the housing; the cover comprises a regulation portion which is configured to regulate the turn of the lever in a state that the cover is attached to the housing so as not to be rotatable toward the first position from a third position positioned between the first position and the second position but to be rotatable between the third position and the second position by being brought into abutment with arm portions or an operation portion of the lever when it is intended to be turned toward the first position; the slider is attached to the housing to be movable in a front-rear direction orthogonal to the up-down direction; the lever has a pinion portion and a pressed portion; the pinion portion has a plurality of teeth; the slider has a rack portion, a press portion and a cam groove; the rack portion has a plurality of teeth; the pinion portion and the rack portion translate turn of the lever into front-rear direction movement of the slider by mutually engaging; the cam groove transmits up-down direction force to the cam shaft of the mating connector according to the front-rear direction movement of the slider; the slider, the cam groove and the cam shaft are configured so that, when the lever is turned from the third position to the second position, the slider is moved forward in the front-rear direction, and the cam groove moves the cam shaft of the mating connector upward in the up-down direction, and thereby the connector and the mating connector are brought into a mated state; and the slider, the cam groove and the cam shaft are configured so that, when the lever is turned from the second position to the third position, the slider is moved rearward in the front-rear direction, and the cam groove moves the cam shaft of the mating connector downward in the up-down direction, and thereby the connector and the mating connector are brought into a removable state. the press portion is configured to be visible when the slider as a single body is seen from a front thereof along the front-rear direction; and the press portion is configured to press the pressed portion to turn the lever toward the second position when the slider is moved forward in the front-rear direction provided that the lever is positioned in the first position. the mating connector comprises a cam shaft; the connector comprises a housing, a lever and a slider; the lever is configured to be attached to the housing to be rotatable between a first position and a second position in a state before the cover is attached to the housing; the cover comprises a regulation portion which is configured to regulate the turn of the lever in a state that the cover is attached to the housing so as not to be rotatable toward the first position from a third position positioned between the first position and the second position but to be rotatable between the third position and the second position by being brought into abutment with arm portions or an operation portion of the lever when it is intended to be turned toward the first position; the slider is attached to the housing to be movable in a front-rear direction orthogonal to the up-down direction; the lever has a pinion portion and a pressed portion; the pinion portion has a plurality of teeth; the slider has a rack portion, a press portion and a cam groove; the rack portion has a plurality of teeth; the pinion portion and the rack portion translate turn of the lever into front-rear direction movement of the slider by mutually engaging; the cam groove transmits up-down direction force to the cam shaft of the mating connector according to the front-rear direction movement of the slider; the slider, the cam groove and the cam shaft are configured so that, when the lever is turned from the third position to the second position, the slider is moved forward in the front-rear direction, and the cam groove moves the cam shaft of the mating connector upward in the up-down direction, and thereby the connector and the mating connector are brought into a mated state; and the slider, the cam groove and the cam shaft are configured so that, when the lever is turned from the second position to the third position, the slider is moved rearward in the front-rear direction, and the cam groove moves the cam shaft of the mating connector downward in the up-down direction, and thereby the connector and the mating connector are brought into a removable state. the press portion is configured to be visible when the slider as a single body is seen from a front thereof along the front-rear direction; and the press portion is configured to press the pressed portion to turn the lever toward the second position when the slider is moved forward in the front-rear direction provided that the lever is positioned in the first position.