To provide an image inspection method for a picture tube and its image inspection device by which the image quality of the picture tube can automatically be decided, without being affected by the outer package frame of a picture tube display device and a size of the picture tube.

The image inspection device is provided with a picture tube support 10 that supports the picture tube 11 so that its screen center Q comes to a prescribed position, a reference position setting device 16 that presses two reference members 15a, 15b with reference marks 14a, 14b toward one side face 13 of the picture tube 11, a test pattern generator 18 the displays a test pattern 17 onto the picture tube 11, an observation device 19 that observes the reference marks 14a, 14b and the test pattern 17 to provide the output of respective position data, a calculation device 20 that calculates a relative distortion amount H of the test pattern 17 with respect to a reference line A which ties the two reference marks 14a, 14b on the basis of the position data, and a quality deciding device 21 that decides the image quality of the picture tube 11 on the basis of the distortion amount H.