Provided is a tire testing machine including: a spindle shaft that rotatably attaches a tire as an inspection target thereto; a tire outer shape measurement sensor that moves close to the tire or moves away from the tire and detects a deformation amount of an outer shape and a diameter of the tire attached to the spindle shaft; and a collision preventing sensor that includes a probe formed in a linear material and a contact detecting portion detecting a state where the probe contacts the tire in order to prevent the tire outer shape measurement sensor from colliding with the tire, wherein the probe has a bent or divided shape in order to ensure a wider contact detecting range contacting the tire.