PURPOSE: To enable accurate focusing by using one of plural solid-stage image pickup elements in common as the detecting element for automatic focus of a modulating system.

CONSTITUTION: A lenscontrol circuit 15 measures level difference between the maximum and minimum values of evaluation values to be outputted from an evaluation value detecting circuit 14 and detects a focusing state, namely, whether the difference between the respective absolute values of the maximum and minimum values is zero or is received in a fixed range including zero. When the focusing state is not obtained, the phase of a change in the evaluation value is collated with the phase of displacement in a solid-state image pickup element 7, which is used also as the detecting element, and it is decided whether current image blurring is on the front focus side or the rear focus side. Then, a focusing direction is detected and the signal of a polarity corresponding to this direction is outputted to a motor driving circuit 16. Afterwards, a focusing motor 3 is rotated in a prescribed direction and a focus lens 2a is moved. When the focusing state is obtained, the rotation of the focusing motor 3 is stopped. Thus, accurate focusing can be executed.