The rotary body driving apparatus comprises: a rotary body having a plurality of reflective surfaces; a rotor being attached to a rotor shaft together with the rotary body; a stator housing having a bearing section; a motor substrate for detecting a rotational position of the rotor; a circular magnetized section for frequency generation facing the motor substrate; a circular frequency generation pattern, which faces the magnetized section, being provided to the motor substrate and disposed close to the magnetized section; a position detecting section, which corresponds to a reference reflective surface of the rotary body, being radially outwardly or inwardly projected from a part of the magnetized section; and a magnetic sensor, which faces the position detecting section, being provided to the motor substrate.