To provide a transmission of a working vehicle in which a machine weight is relatively lightweight by minimizing the number of parts of a transmission mechanism to the utmost, while using an electric motor 9 as a drive source.

In the transmission of the working vehicle comprising a hydraulic stepless transmission device (HTS) 23 supplying driving force to a driving shaft 11a and driving the same by receiving driving force from a driving motor 9 arranged for carrying out advancing, retracting, stop, and acceleration/deceleration, the transmission device 23 has an input side cylinder block 84 housing an input shaft 80 driven by the motor 9, an input side swash plate 82, and a cylinder 84a, a port block 85 having a hydraulic closed circuit receiving oil pressure from the cylinder 84a according to the tilting angle of the swash plate 82 whose tilting angle is decided by a lever 16, an output side cylinder block 86 housing a cylinder 86a receiving oil pressure from the hydraulic closed circuit, an output side swash plate 88 receiving oil pressure from the cylinder block 86a, and an output shaft 81 integral with the plate 88.