A device for measuring the state of contact of a measuring roller of a conveyor belt includes a pressure sensor provided on a rotating surface of the measuring roller, which rotates in contact with an inner peripheral surface of a conveyor belt stretched between pulleys. The pressure sensor detects resistance force acting when the conveyor belt rides over the measuring roller. A rotational position sensor detects the circumferential position, on the rotating surface, of the pressure sensor. The data detected are sequentially wirelessly transmitted to the outside of the measuring roller by a transmission unit installed on the measuring roller, and the transmitted detection data are received by a receiver.