Two-phase permanent magnet synchronous motors are discussed in this paper and the influence of the magnet sizes on cogging torque (CT) is explored. The cogging torque has been calculated using ANSYS/Maxwell software. In more detail, influences of the magnet size, their positioning and orientation to the CT in two basic rotor types were studied. The cogging torque waveform for critical dimensions has been considered using the FFT analysis. The first rotor type is with semi-arc shaped magnets located on the rotor surface. The second motor type features magnets embedded in its rotor. The shape of the stator magnetic circuit has been predetermined.