A developing cartridge comprising: a casing (10; 10A; 10B; 10E; 10F) configured to accommodate developer therein; a storage medium (61; 61A; 61B; 61D; 61E; 61F) including an electric contact surface (611; 611A; 611B; 611D; 611E; 611F); an elastic member (73; 75A; 63B; 62E; 73F) extending in a first direction which crosses the electric contact surface (611; 611A; 611B; 611D; 611E; 611F), the elastic member (73; 75A; 63B; 62E; 73F) configured to be compressed or stretched in the first direction between a first state and a second state; a holder (62; 62A; 62B; 62D; 62E; 62F) including an outer surface (620; 620A) being positioned toward a side of the holder (62; 62A; 62B; 62D; 62E; 62F) in the first direction, the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) being positioned at the outer surface (620; 620A), the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) being movable between a first position and a second position in the first direction relative to the casing (10; 10A; 10B; 10E; 10F) and the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) being movable in a second direction which is different from the first direction relative to the casing (10; 10A; 10B; 10E; 10F); wherein a length of the elastic member (73; 75A; 63B; 62E; 73F) in the first direction is greater in the first state than in the second state, wherein the electric contact surface (611; 611A; 611; 611D; 611E; 611F) is in the first position in a state where the elastic member (73; 75A; 63B; 62E; 73F) is in the first state, and wherein the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) is in the second position in a state where the elastic member (73; 75A; 63B; 62E; 73F) is in the second state, wherein the outer surface includes: a first surface inclined at an acute angle relative to the electric contact surface, the first surface being positioned at one side of the electric contact surface in the second direction, wherein the first surface is a first guide surface, the first guide surface is contactable with a portion of an image forming apparatus when the developing cartridge is attached or detached to or from the image forming apparatus and a second surface inclined at an acute angle relative to the electric contact surface, the second surface being positioned at another side of the electric contact surface in the second direction, wherein the second surface is a second guide surface, the second guide surface is contactable with the portion of an image forming apparatus when the developing cartridge is attached or detached to or from the image forming apparatus a casing (10; 10A; 10B; 10E; 10F) configured to accommodate developer therein; a storage medium (61; 61A; 61B; 61D; 61E; 61F) including an electric contact surface (611; 611A; 611B; 611D; 611E; 611F); an elastic member (73; 75A; 63B; 62E; 73F) extending in a first direction which crosses the electric contact surface (611; 611A; 611B; 611D; 611E; 611F), the elastic member (73; 75A; 63B; 62E; 73F) configured to be compressed or stretched in the first direction between a first state and a second state; a holder (62; 62A; 62B; 62D; 62E; 62F) including an outer surface (620; 620A) being positioned toward a side of the holder (62; 62A; 62B; 62D; 62E; 62F) in the first direction, the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) being positioned at the outer surface (620; 620A), the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) being movable between a first position and a second position in the first direction relative to the casing (10; 10A; 10B; 10E; 10F) and the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) being movable in a second direction which is different from the first direction relative to the casing (10; 10A; 10B; 10E; 10F); wherein a length of the elastic member (73; 75A; 63B; 62E; 73F) in the first direction is greater in the first state than in the second state, wherein the electric contact surface (611; 611A; 611; 611D; 611E; 611F) is in the first position in a state where the elastic member (73; 75A; 63B; 62E; 73F) is in the first state, and wherein the electric contact surface (611; 611A; 611B; 611D; 611E; 611F) is in the second position in a state where the elastic member (73; 75A; 63B; 62E; 73F) is in the second state, wherein the outer surface includes: a first surface inclined at an acute angle relative to the electric contact surface, the first surface being positioned at one side of the electric contact surface in the second direction, wherein the first surface is a first guide surface, the first guide surface is contactable with a portion of an image forming apparatus when the developing cartridge is attached or detached to or from the image forming apparatus and a second surface inclined at an acute angle relative to the electric contact surface, the second surface being positioned at another side of the electric contact surface in the second direction, wherein the second surface is a second guide surface, the second guide surface is contactable with the portion of an image forming apparatus when the developing cartridge is attached or detached to or from the image forming apparatus