To enable a beginner to easily learn how to jump over a buck at a stroke by applying the constitution that a both-leg support board projected toward both lateral sides of a frame body immediately below the uppermost stage of the buck assembled-in a multi-stage form, is provided so as to be capable of being laid and fixed horizontally to the upper end periphery of the frame body.

A buck 12 used in the primary school is assembled by stacking wooden frame bodies 1 to 8 on top of each other, and a cushion material 10 is laid on a plate material 9 fitted to the upper end periphery of the uppermost frame body 1. In addition, the cushion material 10 is covered with a sheet 11. Also, the corner of each of the frame bodies 1 to 8 is provided with an engagement rod 16 projected upward. In this case, a both-leg support board 20 is horizontally laid and fixed between the frame bodies 1 and 2, when a support and jump motion for jumping over the buck 12 at a stroke is learned. Also, in the case of initial learning or practices, the height of the buck 12 is adjusted to a value approximately between 60cm and 70cm. Furthermore, the portion of the both-leg support board 20 beyond the frame body 2 is formed to have such an area as allowing a learner to stand up with open legs placed thereon.