In many industrial applications the conveyor belts thickness monitoring became important. The transport of materials wears out the conveyor belt, that according to the use frequency and material type lead it to reach critical thicknesses and latter its rupture. This work has as main contribution the development of a measurement system of the conveyor belt thickness, using ultrasonic transducers for distance measurement according to time-of-flight principle, without necessity of contact and stop a process in execution by conveyor belt. The experimental results was obtained through a measuring setup with a conveyor belt driven by a motor with speed control, ultrasonic transducers with frequency operation of 40kHz, conditioning circuits and a data acquisition unit.