A stroke detection device includes a stem shaft which is formed of a conductor in a shape of a cylinder, in which a center line of the cylinder is located in parallel to center lines of inner tubes and outer tubes of front forks coupled to a bracket, and which serves as a steering center axis of handlebars of a motorcycle, and a coil which is formed of a conductor and provided so as to be movable in a direction along the center line of the cylinder of the stem shaft with movement in a direction along the center line of the inner tubes and the outer tubes of the front forks, in which a variation in inductance of the coil based on change in length in which the coil and the cylinder of the stem shaft overlap each other is output.