PURPOSE: To make the focus display possible even for a low-contrast object, by comparing two signals indicating the visibility of the image on a photodetector array with two, high and low reference levels and displaying the defocusing direction and the focus in accordance with the comparison result.

CONSTITUTION: Contrast signals F1 and F2 from two photodetector arrays are compared with a high reference level V1 and a low reference level V2 in comparators 41, 42, 43, and 44. If either of signals F1 and F2 is higher than the level V1, outputs of comparators 41 and 42 are inputted to AND circuits 47 and 48, whose one input terminals front focus and rear focus signals from a discrimination processing circuit 32 are inputted to, through OR circuits 45 and 46, and the front focus or the rear focus is displayed on a circuit 49 or 50. If signals F1 and F2 are higher than the level V2 together, outputs of comparators 43 and 45 are inputted to an AND circuit 52, to which the focus signal from the circuit 32 is inputted, through an AND circuit 51, and the focus is displayed on a circuit 53; and thus, the focus display is possible even for a low-contrast object.