An image processing device capable of high-speed detection of a specific shape in an image. In the image processing device, a candidate position calculation section (106) obtains a first candidate position of the center point of a first circle in contact at three points with three sides contained in the shape of an object to be detected. An angle calculation section (106) obtains an angle formed by a normal line drawn from each of the three sides to the first candidate position and a standard line oriented in a specific direction and passing a point at which the normal line and each of the three sides cross. A relative relationship calculation section (106) obtains a relationship of the angle relative to the first candidate position. A recognition section (108) recognizes the shape contained in the given image based on the relative relationship of the angle and a relative relationship of a shape stored in advance.