A cartridge comprising: a housing including a developer accommodating portion configured to accommodate developer therein, a first side wall, and a second side wall opposed to the first side wall in a longitudinal direction, the developer accommodating portion being interposed between the first side wall and the second side wall; a receiving member configured to receive a driving force from outside, located at an opposite side from the developer accommodating portion with respect to the first side wall, and rotatable around a first axis line extending parallel to the longitudinal direction; a rotating member provided between the first and second side walls so as to be rotatable around a second axis line extending parallel to the first axis line, and configured to be rotated by the driving force received by the receiving member; a detection body (50, 102) located at an opposite side from the developer accommodating portion with respect to the second side wall and including a detected part (70, 112) which is configured to be detected by an external detecting unit, wherein the detection body is configured to advance outwards in the longitudinal direction with respect to the second side wall by the driving force received by the receiving member which is transferred through rotation of the rotating member rotating in a first direction, characterized in that the detection body is configured to retract inwards in the longitudinal direction with respect to the second side wall by the driving force received by the receiving member which is transferred through rotation of the rotating member rotating in the first direction, the detection body is reciprocable in a moving direction parallel to the first axis line, and the detection body is movable from a first position where a distance in the moving direction between the detection body and the second side wall is a first distance, via a second position where the distance in the moving direction between the detection body and the second side wall is a second distance larger than the first distance, to a third position where the distance in the moving direction between the detection body and the second side wall is a third distance smaller than the second distance. a housing including a developer accommodating portion configured to accommodate developer therein, a first side wall, and a second side wall opposed to the first side wall in a longitudinal direction, the developer accommodating portion being interposed between the first side wall and the second side wall; a receiving member configured to receive a driving force from outside, located at an opposite side from the developer accommodating portion with respect to the first side wall, and rotatable around a first axis line extending parallel to the longitudinal direction; a rotating member provided between the first and second side walls so as to be rotatable around a second axis line extending parallel to the first axis line, and configured to be rotated by the driving force received by the receiving member; a detection body (50, 102) located at an opposite side from the developer accommodating portion with respect to the second side wall and including a detected part (70, 112) which is configured to be detected by an external detecting unit, wherein the detection body is configured to advance outwards in the longitudinal direction with respect to the second side wall by the driving force received by the receiving member which is transferred through rotation of the rotating member rotating in a first direction, characterized in that the detection body is configured to retract inwards in the longitudinal direction with respect to the second side wall by the driving force received by the receiving member which is transferred through rotation of the rotating member rotating in the first direction, the detection body is reciprocable in a moving direction parallel to the first axis line, and the detection body is movable from a first position where a distance in the moving direction between the detection body and the second side wall is a first distance, via a second position where the distance in the moving direction between the detection body and the second side wall is a second distance larger than the first distance, to a third position where the distance in the moving direction between the detection body and the second side wall is a third distance smaller than the second distance.