A shape inspection apparatus for detecting a surface shape of a strip-shaped body, comprising: a line sensor camera configured to photograph a surface of the strip-shaped body to acquire a line image, a first illumination light source and a second illumination light source that are arranged so as to be symmetric with respect to a specular reflection direction of an optical axis of the line sensor camera, the first illumination light source and the second illumination light source being configured to successively and alternately radiate strip-shaped illumination light at a photographing position of the line sensor camera; a measurement control unit configured to control a lighting timing and a light emission time period of each of the first illumination light source and the second illumination light source, and a line image acquisition timing of the line sensor camera, and a data processing unit configured to process a plurality of line images acquired by the line sensor camera to calculate an inclination of the surface of the strip-shaped body, wherein: a line image acquired by the line sensor camera when a first illumination light is being radiated from the first illumination light source is taken as a first line image, and a line image acquired by the line sensor camera when a second illumination light is being radiated from the second illumination light source is taken as a second line image, the measurement control unit controls the lighting timing and the light emission time period as well as the line image acquisition timing based on a line speed so that photographing ranges are not overlapped between the first line image and the second line image, the line speed being a relative speed between the strip-shaped body and the line sensor camera, and the data processing unit calculates an inclination of the surface of the strip-shaped body based on a differential line image that is obtained based on the first line image and the second line image. a line sensor camera configured to photograph a surface of the strip-shaped body to acquire a line image, a first illumination light source and a second illumination light source that are arranged so as to be symmetric with respect to a specular reflection direction of an optical axis of the line sensor camera, the first illumination light source and the second illumination light source being configured to successively and alternately radiate strip-shaped illumination light at a photographing position of the line sensor camera; a measurement control unit configured to control a lighting timing and a light emission time period of each of the first illumination light source and the second illumination light source, and a line image acquisition timing of the line sensor camera, and a data processing unit configured to process a plurality of line images acquired by the line sensor camera to calculate an inclination of the surface of the strip-shaped body, wherein: a line image acquired by the line sensor camera when a first illumination light is being radiated from the first illumination light source is taken as a first line image, and a line image acquired by the line sensor camera when a second illumination light is being radiated from the second illumination light source is taken as a second line image, the measurement control unit controls the lighting timing and the light emission time period as well as the line image acquisition timing based on a line speed so that photographing ranges are not overlapped between the first line image and the second line image, the line speed being a relative speed between the strip-shaped body and the line sensor camera, and the data processing unit calculates an inclination of the surface of the strip-shaped body based on a differential line image that is obtained based on the first line image and the second line image. a line image acquired by the line sensor camera when a first illumination light is being radiated from the first illumination light source is taken as a first line image, and a line image acquired by the line sensor camera when a second illumination light is being radiated from the second illumination light source is taken as a second line image, the measurement control unit controls the lighting timing and the light emission time period as well as the line image acquisition timing based on a line speed so that photographing ranges are not overlapped between the first line image and the second line image, the line speed being a relative speed between the strip-shaped body and the line sensor camera, and the data processing unit calculates an inclination of the surface of the strip-shaped body based on a differential line image that is obtained based on the first line image and the second line image.