A rehabilitation exercise device for upper and lower limbs includes: a base plate; a mounting plate on which a rehabilitation exercise unit is mounted, the rehabilitation exercise unit including a first support for supporting a user's hand or foot, a second support for supporting a user's forearm or calf, a third support for supporting a user's upper arm or thigh, the mounting plate having a first side that is coupled to the base plate to be horizontally movable along a plate surface thereof; and a link member having opposite sides that are rotatably coupled to the base plate and the mounting plate, respectively, and configured to adjust an angle between the base plate and the mounting plate being rotated when the first side of the mounting plate is moved horizontally along the plate surface of the base plate.