A working fluid supply device is provided with: a first oil pump and a second oil pump driven by an engine; a third oil pump driven by an electric motor; a first unloading valve configured to shift the second oil pump to a no-load operation state; and a controller configured to control a supply state of working oil to an automatic transmission. The controller sets the supply state to a supply state selected from: a first supply state in which the working oil is supplied only from the first oil pump; a second supply state in which the working oil is supplied from the first oil pump and the third oil pump; a third supply state in which the working oil is supplied from the first oil pump and the second oil pump; and a fourth supply state in which the working oil is supplied from the first oil pump, the second oil pump, and the third oil pump.