To solve such problems that in conventional technologies, because of the need for accurately detecting the width of each original position signal, the width varies when the temperature or a power source varies, and so the absolute original position is detected wrongly, and a lot of original position signals and original position signals with wide width are required, and therefore, it is difficult to detect the original position signal accurately.

The absolute position detecting encoder, which detects the absolute position from incremental signals and the original position signal used as a reference signal, has at least two groups of original positions composed so that at least three original position signals are output. A group of the original position signals from the group of original positions has a function for detecting the absolute position.