PURPOSE: To measure a distance with infrared rays with accuracy even for a camera capable of varying a focal distance.

CONSTITUTION: The camera is provided with an automatic focusing mechansim for measuring the distance by an infrared ray projecting part 4a and an infrared ray receiving part 4b, a focal distance varying mechanism and a variable apex angle prism 5 arranged in front of the infrared ray projecting part 4a, and the apex angle α of the variable apex angle prism 5 can be adjusted by a driving means, and the apex angle α of the variable apex angle prism 5 is adjusted in accordance with the varied focal distance so as to correct the irradiating direction of the infrared ray, and then, the position of a display part on a finder screen is always coincident with the position actually irradiated with the infrared ray.