To provide a transmission which has a small longitudinal size, is compact, controls continuously speed change ratio from infinity to acceleration condition, and stabilizes a first pump ring of a speed change control material using plunger thrust.

A first plunger 14 group of a radial-type first hydraulic pump P1 and a second plunger 24 group of a radial-type second oil pressure pump P2 which is connected to the first hydraulic pump P1 through a hydraulic closed circuit are installed on a common cylinder body 12 fixed to an input shaft 1, and a first pump ring 15 operating the first plunger 14 group is supported in a mission case 5 by a main shaft 17 in order to make the eccentric direction and the eccentric amount of the first pump ring 15 variable in relation to the cylinder body 12. The main shaft is arranged in the position where the sum of turning force of the first plunger 14 group thrust for the first pump ring 15 becomes zero when the eccentric amount of the first pump ring 15 is zero, and a second pump ring 25 operating the second plunger 24 group is integrated with the output shaft 2.