PURPOSE: To simplify the constitution and to facilitate the adjustment by successively differentiating variable density picture data obtained by picking up the image of an object to calculate the differential value of the picture and integrating this value and outputting the integral value as the value indicating the adjustment states of focus and diaphragm.

CONSTITUTION: This device consists of a camera 3 and a signal processing part 4 which takes the picture signal from the camera 3 as the input and subjects it to prescribed signal processing. Variable density picture data from an A/D converter 5 is inputted to a differential operation part 6 for differential processing, and a differential value DD is given to an integral operation part 7 and is integrated. An integral value ΣDD from the integral operation part 7 is read by a CPU 9 through a data bus 8. The integral value is outputted as the value indicating the adjustment states of focus and diaphragm, and focus and diaphragm are so adjusted that the output value is maximum, and focus and diaphragm are set to optimum states. Thus, a focus and aperture adjusting device is obtained which simplifies the constitution and facilitates the adjusting work.