To provide a detecting method for the phase angle of a position transmitting apparatus, in which a high-accuracy measured result can be obtained stably for a long period.

A sine signal U0 (α)=A.sinα and a cosine signal U1 (α)=A.cosα are generated by a sensor, and their output signals are digitally converted. On the basis of their digital output signals, a primary coupling U2=U0+U1 and a primary coupling U3=U1-U0 are generated. When the sign of the primary couplings is investigated, a circulating binary code q1 and a circulating binary code q0 are generated, and a quadrant to which an angle of rotation α belongs is decided. According to the found quadrant, a dividing operation of U2/U1 or U2/U0 is performed. Even when any of a divisor U1 or a divisor U0 is selected, only a component at 1/2 or higher of their maximum value is used as the divisor. Its divided result is used as an address, an angle table which is stored in advance is collated, and position data α whose bit resolution is sufficient is outputted. Since the digital conversion is performed immediately after the generation of an analog sine signal, all processing operations after that are performed completely by a digital system.