A variable optical attenuator is constituted of input/output optical systems, a birefringent member provided at output sides of the input/output optical systems, a liquid-crystal member capable of individually varying polarizing states of input beams exiting the birefringent member, and a reflection member which reflects light passing through the liquid-crystal member, to thereby cause the light to return to an output lens of the input/output optical systems by way of the liquid-crystal member and the birefringent member. Thus, there can be provided a variable optical attenuator which is more compact and less expensive than a related-art variable optical attenuator.