In this paper, we describe the design and implementation of a one-chip camera device for a capsule endoscope. This experimental chip integrates peripheral circuits required for the capsule endoscope and the wireless transmission function based on a data transmission method using human body conduction. The integrated functional blocks include an image array, a timing generator, a clock generator, a voltage regulator, a 10b cyclic A/D converter, and a BPSK modulator. It can be operated autonomously with 3 pins (VDD, GND, and DATAOUT). A prototype chip which has 320x240 effective pixels was fabricated using 0.25μm CMOS image sensor process and the autonomous imaging was demonstrated. The chip size is 4.84mmx4.34mm. With a 2.0 V power supply, the analog part consumes 950µW and the total power consumption at 6 fps (20MHz carrier frequency) is about 3mW.