An electric wheelchair comprises: a chair assembly and a wheel assembly. The wheel assembly is mounted at the bottom of the chair assembly. The chair assembly includes a seat, a first frame, a second frame, and a third frame, which are pivotally connected to form a four-bar linkage mechanism, so that the seat and the respective frames of the electric wheelchair will be folded synchronously in the same direction when the electric wheelchair is being folded, and the folding direction of the chair assembly is vertical to the axis of the drive wheels of the wheel assembly, thus allowing the disabled user to fold the chair assembly and to disassemble the wheel assembly quickly and effortlessly.