To practice pitching concerning control in his own right without other's help and diagnose himself concerning control.

This trainer is composed of a front photoelectric sensor which is provided in a measuring frame 1 which is provided on a home base with having a depth toward vertical and horizontal directions every fixed space, a back photoelectric sensor which is provided toward vertical and horizontal directions of the frame with leaving fixed distance from the front photoelectric sensor and a controller 7 which judges whether ball or strike based on horizontal and vertical positions of the photoelectric sensor when light which is irradiated from the photoelectric sensor is interrupted and has a function that calculates and measures speed of a ball by a time which is required until when the back photoelectric sensor is interrupted in the beginning after when the front photoelectric sensor is interrupted. Furthermore, the trainer is composed of a display means 6 which shows whether strike of a pitched ball is excited, or not, a position of the passed ball and speed of the ball every time a pitcher pitches the ball toward the frame 1.