A substrate transfer device includes: a planar motor provided in a transfer chamber and including an array of coils; a transfer unit configured to move above the planar motor; and a controller configured to control supply of a current to the array of the coils, wherein the transfer unit includes: a first base including an array of first magnets and configured to move above the planar motor; a second base including an array of second magnets and configured to move above the planar motor, the second base being arranged coaxially with the first base; and at least one arm configured to be extended/contracted by rotating the second base relative to the first base.