A laboratory prototype model of a reel system has been made as the first step of an in-house hardware study of the tether system in space. The model is consisted of two main parts, i. e., a Reel Drum Driving (RDD) unit (25 kg weight) and a Power Supply/Signal Processing (PSSP) unit (32 kg weight). The tether (0.8 mm in diameter and 300 m long) consists of a Kevlar fiber core and a nylon fiber jacket. Following the preliminary functional test, a computer-controlled functional test has been carried out using a 32-bit personal computer as a control processor. The tests have shown that the stable operations of reel-out and reel-in are possible by tension control in both cases of a small tension (light end weight) and a high frequency input to the reel drum driving motor.