A two-phase electric motor includes first and second coil groups and a magnet group. In the magnet group, N poles and S poles are disposed alternatively opposite the first and second coil groups. The first and second coil groups are disposed at positions that are out of phase with each other by an odd multiple of π/2 in electrical angles. The coils of the first and second coil groups have substantially no magnetic material cores, and the electric motor has substantially no magnetic material yoke for forming a magnetic circuit.