An apparatus comprising: a main body of the apparatus; a unit detachably attached to the main body; a unit moving device (60, 70) for provision between the main body of the apparatus and the unit that is removable from the main body of the apparatus, the unit moving device (60, 70) being arranged to move the unit in the main body of the apparatus, the unit moving device (60, 70) comprising: an elastic member, provided on one of the unit or the main body of the apparatus; a sliding member connected to the elastic member; and an accumulator, provided on the other of the unit or the main body, wherein the accumulator comprises a guiding member configured to guide the sliding member in a case where an operation to insert the unit to a mounting position of the main body and an operation to pull out the unit from the mounting position of the main body are performed; wherein in a case in a case where the operation to insert the unit to the mounting position of the main body is performed, the sliding member is guided along a first inclined surface of the guiding member, and accordingly the elastic member is stretched and an elastic force is accumulated in the elastic member; wherein when the sliding member passes through the first inclined surface of the guiding member and reaches to a second inclined surface of the guiding member, the sliding member descends along the second inclined surface, the sliding member presses the second inclined surface by using the elastic force accumulated in the elastic member and the unit is pulled to the mounting position in the main body; and wherein in a case where the operation to pull out the unit from the mounting position of the main body is performed, the sliding member passed through the second inclined surface of the guiding member presses, by using an elastic force remained in the elastic member, a third inclined surface of the guiding member, and the unit is pushed from the mounting position in the main body. a main body of the apparatus; a unit detachably attached to the main body; a unit moving device (60, 70) for provision between the main body of the apparatus and the unit that is removable from the main body of the apparatus, the unit moving device (60, 70) being arranged to move the unit in the main body of the apparatus, the unit moving device (60, 70) comprising: an elastic member, provided on one of the unit or the main body of the apparatus; a sliding member connected to the elastic member; and an accumulator, provided on the other of the unit or the main body, an elastic member, provided on one of the unit or the main body of the apparatus; a sliding member connected to the elastic member; and an accumulator, provided on the other of the unit or the main body, wherein the accumulator comprises a guiding member configured to guide the sliding member in a case where an operation to insert the unit to a mounting position of the main body and an operation to pull out the unit from the mounting position of the main body are performed; wherein in a case in a case where the operation to insert the unit to the mounting position of the main body is performed, the sliding member is guided along a first inclined surface of the guiding member, and accordingly the elastic member is stretched and an elastic force is accumulated in the elastic member; wherein when the sliding member passes through the first inclined surface of the guiding member and reaches to a second inclined surface of the guiding member, the sliding member descends along the second inclined surface, the sliding member presses the second inclined surface by using the elastic force accumulated in the elastic member and the unit is pulled to the mounting position in the main body; and wherein in a case where the operation to pull out the unit from the mounting position of the main body is performed, the sliding member passed through the second inclined surface of the guiding member presses, by using an elastic force remained in the elastic member, a third inclined surface of the guiding member, and the unit is pushed from the mounting position in the main body.