PURPOSE: To evaluate a screen by an inference carried out based on a few rules that are previously and empirically determined and without setting detailed conditions to various screens by applying fuzzy inference for evaluation of the states of the screen.

CONSTITUTION: The normalization circuits 51-56 divide respective luminance evaluation values Y1-Y6 of respective regions by the areas S1-S6 and output the luminance evaluation values per unit area for respective regions as the normalized luminance evaluation values V1-V6. A priority deciding circuit 57 decides the priority (weight) Wk of each region by fuzzy inference. Then the weighting circuit 61-66 receive the priority Wk of each area and apply the weighting to the priorities W1-W6 of the areas to perform the so-called priority processing. A weighted means circuit 67 outputs the weighted means value Z2. An optimum target level P0 is multiplied by the division value (m), i.e., the correction value that is defined as a ratio between the value Z2 and the simple means value Z1. Then the resultant value is compared with the output of an integrator 90 that shows the luminance level of an image pickup video signal. Thus the optimum exposure control is carried out.