Provided is an inside drum-type tire testing device which can significantly improve workability and test accuracy and reliably impart sufficient strength to eliminate a concern for insufficient strength, and moreover enables a reduction in occupied floor space by a reduction in the size of the device. A tire testing device is provided with an inside-drum type cylindrical rotating drum (1), and a stationary holding member (2) which surrounds the rotating drum (1) on the outer peripheral side via a rotation guide (3), and a linear motor (4) for rotationally driving the rotating drum (1) is disposed between the rotating drum (1) and the holding member (2).