Studies have been carried out on a rail brake applying linear induction motor technology. This brake is capable of generating contactless braking force. In addition to the contactless braking, no on-board power supply for energizing this brake is required by using dynamic braking. In order to place this brake into service however a self-diagnosis method for checking the soundness of the device is necessary. Therefore, a condition monitoring method for this brake using an excitation inverter, not using dedicated sensors, was considered and examined on a test bench with a roller rig. Results from these tests clarified that the devised method is useful for self-diagnosis.