An image pickup apparatus capable of generating a motion picture and a still picture. An amount of exposure in a still imaging mode is increased as compared with the amount of exposure for mode is increased as compared with the amount of exposure for one field in the motion picture imaging mode, preferably twice as large as the latter. In the still picture mode, electric charges are swept out from a CCD by an exposure control simultaneously with closing of a diaphragm for adjusting the amount of exposure. Upon occurrence of error in the closing operation of the diaphragm, the amount of exposure in the still picture mode is set to a design value. On the basis of difference between the design value and an actually measured value of the amount of exposure, gain for video signal is corrected. In the motion picture mode, the diaphragm and the electronic shutter speed is adjusted for preventing flicker from making appearance under illumination of a fluorescent lamp in indoor photographing. The adjusted speed can be 1/100 sec.