A modular electronic device includes a frame and a module disposed in the frame. The frame has a slot and a recess in the slot. The module is disposed in the slot. The module includes a casing, a rail component disposed in casing and having a rail, a push rod slid in the rail, a supporting piece connected to push rod, a magnetic component disposed on supporting piece, and a latching member disposed in casing. Magnetic component includes a first magnet and a second magnet having opposite magnetic directions. Latching member is made of magnetic material. Casing has an opening arranged facing frame. Magnetic component is moved relative to latching member when push rod is slid along rail component. Magnetic component provides a repulsion force to push latching member protruding from opening and engaging with recess or provides an attraction force to restore latching member being contained in casing.