To enable a coach to view the pitching training state from the side part of a player, to clearly photograph a training state by a camera or a video so as to be used for reference as a record later and to prevent a pitching training instrument from falling off at the time of repetitive pitching training in the pitching training instrument of a bag-shaped bag body.

In this pitching training instrument 10, the bag-shaped bag body main body 11 on an outer side is provided with the inner bag 11' of double bottoms at the tip and is made of transparent resin and the holding relation of a hand and a ball is viewed and photographed. Further, to the bag-shaped bag body main body 11, a cover cylindrical body 11" is attached from the bag port 4 to an elbow, tightening is lightly and surely performed so as not to cause a skin inflammation by plural tightening bands 7 and the pitching training instrument 10 is prevented from falling off from an arm through centrifugal force by the repetitive pitching training.