A substrate transfer device includes: a traveling unit including a traveling wheel that travels on a rail to transfer a substrate in a first direction; a rail unit including the rail and a rail protrusion protruding from the rail in a second direction different from the first direction; and a sensor unit including a first sensor and a second sensor, wherein the first sensor senses the traveling unit, and the second sensor senses the rail protrusion, wherein the first and second sensors are placed at the same position as each other along the rail on a basis of the first direction.