To enhance effect of learning correct jump by putting a left/right set of marks to be touched by both hands at vaulting on specified left/right positions on a cloth, to encourage people to touch their both hands at the correct positions on the top of a buck for the purpose to enable them to vault the buck in a correct posture.

The buck consists of a trunk section 2 and a head 3 that is put on the top of the trunk section 2. The trunk section 2 consists of plural wooden frames 4 that can vertically be mated with each other. Changing a stacking-stage number of these wooden frames 4 can adjust the height of the buck 1. This head 3 consists of a wooden base frame that can be mated with the top wooden frame 4 of the trunk section 2 and a sailcloth 5 stretched over the top surface of the wooden base frame on which the first and second marks 6 and 7 in the form of both hands being opened, are delineated. These marks 6 and 7 are provided as a guide for positioning of touching both hands at vaulting. The first marks 6 are used upon vaulting the buck in the A-direction, and the second marks 7, in the B-direction, respectively.