A tire testing apparatus includes: a lower rim that is formed with a lower through hole, and a rim-side inclined surface that increases in diameter in a downward direction of an inner peripheral surface of a lower end portion of the lower through hole; an upper rim that is held to face the lower rim; an insertion part capable of being inserted through the lower through hole; and an apparatus-side inclined surface that is provided at a lower end portion of the insertion part, increases in diameter from an outer peripheral surface of the insertion part in the downward direction, and is capable of coming into contact with the rim-side inclined surface.