To provide an automatic aperture control means for a television camera not causing hunting.

The output signal of a television camera 1 is processed by a signal processing section 2 and displayed on a monitor 3. The output signal of the television camera 1 is received by the signal processing section 2 and an integration device 5 integrates the signal by one field to obtain object illuminance data of the television camera 1. The object illuminance data are given to an MPU 7 for each field as a digital signal by an A/D converter 6. The MPU 7 writes the data once to a storage section 8 according to the procedure of an aperture control section 9a and reads the object illuminance data by the number of fields stored in the storage section 8 and to obtain the mean value and it is compared with a reference value stored in a reference storage section 9b and a coefficient stored in a coefficient storage section 9c is multiplied and the result is outputted to an aperture control section 4 as an aperture control quantity and the aperture of the television camera 1 is controlled depending on the aperture control quantity.