A developing cartridge comprising: a casing (10;10A;10B;10C;10E;10F) for accommodating developer therein; a developing roller (30;30F) rotatable about an axis extending in a first direction and positioned at one side of the casing (10;10A;10B;10C;10E;10F) in a second direction; a storage medium (61;61A;61B;61C;61D;61E;61F) having an electric contact surface (611;611A;611B;611C;611D;611E;611F); a holder (62;62A;62B;62C;62D;62E;62F) movable relative to the casing (10;10A;10B;10C;10E;10F) in the second direction between a first position and a second position, the holder (62;62A;62B;62C;62D;62E;62F) having an outer surface (620;620A) at which the electric contact surface (611;611A;611B;611C;611D;611E;611F) is positioned, the holder (62;62A;62B;62C;62D;62E;62F) positioned at a side of the casing (10;10A;10B;10C;10E;10F) in the first direction; and characterized by a holder cover (45;45F) positioned at the side of the casing (10;10F) in the first direction, and covering at least a portion of the holder (62;62F), wherein the holder cover (45;45F) has one of a first recessed portion and a first through-hole (451 a,451 b;451 F), and wherein the holder (62;62F) includes a first boss (621a,621b;621aF) extending in the first direction and inserted through one of the first recessed portion and the first through-hole (451a,451b;451F), the first boss (621a,621b;621aF) being movable in the second direction relative to one of the first recessed portion and the first through-hole (451 a,451 b;451F) when the holder (62;62F) moves relative to the casing (10;10F) in the second direction between the first position and the second position. a casing (10;10A;10B;10C;10E;10F) for accommodating developer therein; a developing roller (30;30F) rotatable about an axis extending in a first direction and positioned at one side of the casing (10;10A;10B;10C;10E;10F) in a second direction; a storage medium (61;61A;61B;61C;61D;61E;61F) having an electric contact surface (611;611A;611B;611C;611D;611E;611F); a holder (62;62A;62B;62C;62D;62E;62F) movable relative to the casing (10;10A;10B;10C;10E;10F) in the second direction between a first position and a second position, the holder (62;62A;62B;62C;62D;62E;62F) having an outer surface (620;620A) at which the electric contact surface (611;611A;611B;611C;611D;611E;611F) is positioned, the holder (62;62A;62B;62C;62D;62E;62F) positioned at a side of the casing (10;10A;10B;10C;10E;10F) in the first direction; and characterized by a holder cover (45;45F) positioned at the side of the casing (10;10F) in the first direction, and covering at least a portion of the holder (62;62F), wherein the holder cover (45;45F) has one of a first recessed portion and a first through-hole (451 a,451 b;451 F), and wherein the holder (62;62F) includes a first boss (621a,621b;621aF) extending in the first direction and inserted through one of the first recessed portion and the first through-hole (451a,451b;451F), the first boss (621a,621b;621aF) being movable in the second direction relative to one of the first recessed portion and the first through-hole (451 a,451 b;451F) when the holder (62;62F) moves relative to the casing (10;10F) in the second direction between the first position and the second position.