A cartridge comprising: a housing (10, 30); a storage medium comprising an electrical contact surface; and a holder movable relative to the housing, the holder including: a first holder member holding the electrical contact surface and including at least one pawl (52, 53), the first holder member having one end surface in a first direction crossing the electrical contact surface, and the electrical contact surface being positioned at the one end surface; and a second holder member movable relative to the first holder member, the second holder member including at least one corner part (62, 63) engageable with the at least one pawl to provide an engaging portion therebetween, the second holder member having one end portion at one side and an end face at another side in the first direction, and the second holder member having a through-hole (67, 68) that is open at the end face at the another side, the engaging portion being accessible from an outside of the holder through the through-hole (67, 68), characterised in that the at least one pawl includes a first pawl and a second pawl, wherein the at least one corner part includes: a first corner part engageable with the first pawl to provide a first engaging portion therebetween; and a second corner part engageable with the second pawl to provide a second engaging portion therebetween, wherein the through-hole includes: a first through-hole through which the first engaging portion is accessible from the outside of the holder; and a second through-hole through which the second engaging portion is accessible from the outside of the holder, and wherein the second through-hole extends from the another side in the first direction, and the first through-hole extends from the another side in the first direction. a housing (10, 30); a storage medium comprising an electrical contact surface; and a holder movable relative to the housing, the holder including: a first holder member holding the electrical contact surface and including at least one pawl (52, 53), the first holder member having one end surface in a first direction crossing the electrical contact surface, and the electrical contact surface being positioned at the one end surface; and a second holder member movable relative to the first holder member, the second holder member including at least one corner part (62, 63) engageable with the at least one pawl to provide an engaging portion therebetween, the second holder member having one end portion at one side and an end face at another side in the first direction, and the second holder member having a through-hole (67, 68) that is open at the end face at the another side, the engaging portion being accessible from an outside of the holder through the through-hole (67, 68), characterised in that the at least one pawl includes a first pawl and a second pawl, a first holder member holding the electrical contact surface and including at least one pawl (52, 53), the first holder member having one end surface in a first direction crossing the electrical contact surface, and the electrical contact surface being positioned at the one end surface; and a second holder member movable relative to the first holder member, the second holder member including at least one corner part (62, 63) engageable with the at least one pawl to provide an engaging portion therebetween, the second holder member having one end portion at one side and an end face at another side in the first direction, and the second holder member having a through-hole (67, 68) that is open at the end face at the another side, the engaging portion being accessible from an outside of the holder through the through-hole (67, 68), characterised in that the at least one pawl includes a first pawl and a second pawl, wherein the at least one corner part includes: a first corner part engageable with the first pawl to provide a first engaging portion therebetween; and a second corner part engageable with the second pawl to provide a second engaging portion therebetween, wherein the through-hole includes: a first through-hole through which the first engaging portion is accessible from the outside of the holder; and a second through-hole through which the second engaging portion is accessible from the outside of the holder, and wherein the second through-hole extends from the another side in the first direction, and the first through-hole extends from the another side in the first direction.