To provide an imaging apparatus equipped with an automatic exposure control circuit which performs stable exposure control and which is free from sense of oddness.

In the imaging apparatus, having an imaging device for photoelectrically converting imaging light into a video signal, and performing digital signal processing by converting an analog video signal from the imaging device into a digital signal, iris control for controlling an iris, in order to keep an appropriate exposure level with the change of the brightness of a subject is constituted of a detection means for detecting the opening of the iris, an arithmetic circuit for arithmetically operating a control signal for controlling the gain of an iris braking circuit according to the opening position information of the iris obtained from the detection means, and a means for varying the gain of the iris braking circuit, based on the result of the arithmetic operation of the arithmetic circuit.