A development device to develop a latent image formed on a latent image carrier with two-component developer consisting essentially of toner and carrier, the development device comprising: a casing; a developer container housed in the casing, for containing the developer; a hollow, cylindrical nonmagnetic developer carrier rotatably disposed within the casing, to transport the developer while rotating, the developer carrier exposed partly through an opening of the casing and facing the latent image carrier in a development area; a magnetic field generator disposed inside the developer carrier, having multiple magnetic poles including an attraction pole to attract the developer from the developer container to the developer carrier, a developer conveyance pole (P2,P3) to keep the developer on the developer carrier downstream from the development area in a direction in which the developer carrier rotates to a developer release portion, and a release pole to separate the developer from the developer carrier and to return the developer to the developer container; a developer agitator disposed in the developer container, to agitate the developer while transporting the developer in an axial direction of the developer carrier; and a developer regulator housed in the casing, to adjust a layer thickness of the developer carried on the developer carrier, wherein multiple recesses are formed in the outer circumferential surface of the developer carrier at intervals, a predetermined casing gap is positioned adjacent the opening, wherein the predetermined casing gap is a distance between an outer circumferential surface of the developer carrier and an inner wall of the casing at a portion downstream from the opening formed in the casing and upstream from the developer release portion in the direction in which the developer carrier rotates, wherein the casing gap is configured to cause airflow, flowing into the development device, that transports the developer in the rotational direction of the developer carrier when the developer on the developer carrier passes through the casing gap between the inner wall of the casing and the outer circumferential surface of the developer carrier, wherein the predetermined casing gap is configured to face one of the multiple magnetic poles of the magnetic field generator, wherein an arrangement pitch (Pc) between adjacent recesses in the circumferential direction of the developer carrier is smaller than a circumferential length of the developer carrier corresponding to the half width of the magnetic flux density of the developer conveyance pole (P2,P3) in a direction perpendicular to an axial direction of the developer carrier. a casing; a developer container housed in the casing, for containing the developer; a hollow, cylindrical nonmagnetic developer carrier rotatably disposed within the casing, to transport the developer while rotating, the developer carrier exposed partly through an opening of the casing and facing the latent image carrier in a development area; a magnetic field generator disposed inside the developer carrier, having multiple magnetic poles including an attraction pole to attract the developer from the developer container to the developer carrier, a developer conveyance pole (P2,P3) to keep the developer on the developer carrier downstream from the development area in a direction in which the developer carrier rotates to a developer release portion, and a release pole to separate the developer from the developer carrier and to return the developer to the developer container; a developer agitator disposed in the developer container, to agitate the developer while transporting the developer in an axial direction of the developer carrier; and a developer regulator housed in the casing, to adjust a layer thickness of the developer carried on the developer carrier, wherein multiple recesses are formed in the outer circumferential surface of the developer carrier at intervals, a predetermined casing gap is positioned adjacent the opening, wherein the predetermined casing gap is a distance between an outer circumferential surface of the developer carrier and an inner wall of the casing at a portion downstream from the opening formed in the casing and upstream from the developer release portion in the direction in which the developer carrier rotates, wherein the casing gap is configured to cause airflow, flowing into the development device, that transports the developer in the rotational direction of the developer carrier when the developer on the developer carrier passes through the casing gap between the inner wall of the casing and the outer circumferential surface of the developer carrier, wherein the predetermined casing gap is configured to face one of the multiple magnetic poles of the magnetic field generator, wherein an arrangement pitch (Pc) between adjacent recesses in the circumferential direction of the developer carrier is smaller than a circumferential length of the developer carrier corresponding to the half width of the magnetic flux density of the developer conveyance pole (P2,P3) in a direction perpendicular to an axial direction of the developer carrier.