To adjust a focus with high precision and also prevent degradation in the resolution of an observation use video signal on the basis of the video signal even when the luminance of an object is low.

The electronic camera having a focus adjustment function is provided with a focus lens 12 that forms an object image onto an image pickup face, a CCD image pickup element 14 that converts the object image formed by the focus lens 12 into a video signal, and an AF processing circuit 32 that adjusts the focus of the focus lens 12 on the basis of the video signal from the image pickup element 14. Then as a video signal used for focus adjustment, when the luminance B of an object is sufficiently high (B≥B1), the video signal is used as it is, when the luminance is comparatively low (B1>B>B2), the video signal resulting from summing signal charges of pixels adjacent in the vertical direction in the image pickup element 14 is used, and when the luminance is very low (B2≥B), the video signals are summed and an AGC circuit 17 amplifies the sum.