An image processing apparatus comprising: an image obtainment means adapted to obtain a three-dimensional medical image; a display control means adapted to display the obtained three-dimensional medical image on a display screen; an input unit including a pointing device for receiving an input position by a user on the display screen, and an input operation by the user; and an image processing means adapted to perform region specification processing on the displayed three-dimensional medical image based on the received input operation, wherein the region specification processing is adapted to specify a closed curve on the display screen based on the received input operation, and to delete a part of the three-dimensional medical image, and the part being an inside or an outside of a cylinder extending from the specified closed curve toward the depth direction of the display screen, characterized in that the image processing means is adapted to perform said region specification processing when the received input position is located in a region other than a center region of the display screen, and to perform rotation processing on the displayed three-dimensional medical image based on the received input operation when the received input position is located in the center region of the display screen, wherein the image processing means is further adapted to perform rotation processing by calculating a direction and a distance from a start point to an end point of a drag operation of the pointing device on the display screen, the start point corresponding to a received input position in the center region and the end point corresponding to a position in a region other than the center region, and wherein the direction determines the rotation direction and the distance determines the rotation amount. an image obtainment means adapted to obtain a three-dimensional medical image; a display control means adapted to display the obtained three-dimensional medical image on a display screen; an input unit including a pointing device for receiving an input position by a user on the display screen, and an input operation by the user; and an image processing means adapted to perform region specification processing on the displayed three-dimensional medical image based on the received input operation, wherein the region specification processing is adapted to specify a closed curve on the display screen based on the received input operation, and to delete a part of the three-dimensional medical image, and the part being an inside or an outside of a cylinder extending from the specified closed curve toward the depth direction of the display screen, characterized in that the image processing means is adapted to perform said region specification processing when the received input position is located in a region other than a center region of the display screen, and to perform rotation processing on the displayed three-dimensional medical image based on the received input operation when the received input position is located in the center region of the display screen, wherein the image processing means is further adapted to perform rotation processing by calculating a direction and a distance from a start point to an end point of a drag operation of the pointing device on the display screen, the start point corresponding to a received input position in the center region and the end point corresponding to a position in a region other than the center region, and wherein the direction determines the rotation direction and the distance determines the rotation amount.