Abstract: A body fat thickness measurement apparatus. The apparatus comprises a transducer, an output control circuit, and a signal control device. The transducer outputs ultrasound waves with a frequency above 10 MHz and receives the ultrasound reflected back by the subject. The transducer then converts the reflected ultrasound to an analog signal. The output control circuit outputs a high voltage pulse depending on a predetermined time period or a position of the transducer. The signal control device receives the analog signal and converts it to a digital signal. A processor converts the digital signal into a video signal to be displayed on a monitor.