PURPOSE: To obtain the video image pickup device which can secure normal operation without causing a timing error even when the source voltage drops by varying a clock frequency supplied to a digital signal processing circuit according to the power source capacity.

CONSTITUTION: This video image pickup device converts the image signal from an image pickup element into a digital signal and inputs it to the digital signal processing circuit, and then converts it into an R, a G, and a B signal and an analog signal and outputs them as a composite video signal. When the power source capacity becomes less than a prescribed value, a contact (b) of the switch of a switch circuit 7 is made ON and frequency-divided clock pulses are sent out through a frequency dividing circuit 8. The clock pulses sent out of the switch circuit 7 are supplied to only the digital signal processing circuit and clock pulses of actual frequency from an oscillation circuit 9 are sent out to other circuits. Thus, the power consumption of the digital signal processing circuit is reduced and a margin to the delay of the circuit increases, so that the operation is stabilized.