A substrate transfer apparatus for loading and unloading substrates in a reaction chamber, includes: an arm having a distal end which is laterally movable in a straight line direction; and end-effectors for loading and unloading substrates in a reaction chamber, which include a lower end-effector and an upper end-effector. One of the lower end-effector or the upper end-effector is movably coupled to the arm at a distal end of the arm, and the other end-effector is fixed to the movably coupled end-effector. The fixed end-effector is fixed to the movably coupled end-effector.