The invention provides a control apparatus of a working vehicle. The working vehicle includes a hydraulic circuit which is a closed circuit having a hydraulic pump driven by an engine and two hydraulic motors and in which the two hydraulic motors are connected in parallel to the hydraulic pump. A clutch is released or engaged so that a power is transmitted to an output shaft of one hydraulic motor via the clutch in the working vehicle. The working vehicle travels by a drive force of the one or two hydraulic motors. The control apparatus is characterized by comprising: a load detection unit configured to determine a working vehicle load of the working vehicle from a throttle output amount and an engine speed of the engine; and a control unit configured to execute control for reducing a pump injection amount of the hydraulic pump under a restriction of an upper limit injection amount of the hydraulic pump predetermined based on the working vehicle load determined by the load detection unit at a time of release shift control of the clutch and execute control for increasing a pump injection amount of the hydraulic pump under a restriction of a lower limit injection amount of the hydraulic pump predetermined based on the working vehicle load determined by the load detection unit at a time of engagement shift control of the clutch.