This paper presents a study of the vibration and noise of an internal gear drive. A running test was carried out using test internal gear pairs with five contact ratios and a power circulating-type internal gear testing machine. The circumferential vibration acceleration of the test internal gear, the tooth root stress, the torsional vibration of the internal gear shaft, and the gear noise were measured. By comparison with measured data, the dynamic characteristics of the internal gear drive were discussed.