To provide a ball type transmission which sets a speed change ratio over a wide range, while suppressing increase of a size of the unit.

This ball type shifting gear unit 10 is provided with a housing 11, a first power plate 12 having a first guide channel 12a having a cycloidal wave shape and fixed to the housing 11, a second power plate 15 having a second guide channel 15a having the cycloidal wave shape on a face opposing to the first guide channel 12a and a third guide channel 15b having the cycloidal wave shape on a face on the opposite side, a third power plate 18 having a fourth guide channel 18a having the cycloidal wave shape on a face opposing to the third guide channel 15b and supported on the housing 11 rotatably, a plurality of balls 25 rolling between the first guide channel 12a and the second guide channel 15a, a plurality of balls 27 rolling between the third guide channel 15b and the fourth guide channel 18a, and a crank shaft 20 for letting the second power plate 15 perform eccentric movement relative to the center of the first guide channel 12a.