Control of belt-drive continuously variable transmission

A controller (50) controls the supply of oil pressure to a primary pulley (41) and a secondary pulley (42) of a belt-drive continuously variable transmission (1) in accordance with the depression amount of an accelerator pedal (81) of a vehicle. When slippage is detected in a V-belt (43) that is wrapped around the primary pulley (41) and secondary pulley (42), the controller (50) reduces the output torque of an engine (70) of the vehicle to stop the V-belt (43) from slipping. Meanwhile, damage to the V-belt (43) caused by slippage is prevented by reducing the oil pressure supply to the secondary pulley (42).