A video camera (100) for transmitting image data with saved electric power from an image pickup device to an image processing device is provided with a C-MOS image sensor (110) for reading out the image pickup data based on a standard clock signal (CLK0) as standards, a frequency multiplying circuit (121) for generating a high speed clock signal (CLK1), a rearranging circuit (122) for replacing the image pickup data with bit data trains, a data output unit (120) for each data transmitter to sequentially transmit each bit data train to the outside based on the high speed clock signal (CLK1), and a system controller (400) for driving the data transmitters (124), the number of which is in proportion to a transmission speed.