The drive tube-related troubles, i.e., tube bending or disconnection, in the NIPRO-ventricular assist device(VAD)might directly cause cease of the blood pump. However, the driver which is usually used in clinical practice does not contain a safeguard for detecting such drive tube-related accidents. Therefore, we developed an external detecting device that mainly incorporates a vibration sensor in order to determine the drive status of the blood pump. First, the response of the device was assessed using a mock circulation. Next, this device was mounted and examined in two patients when pump-off test was performed. The mock circulation results showed that this device could detect not only disconnection and complete occlusion of the drive tube but also incomplete occlusion of the drive tube, regardless of the settings of the VAD or bending part of the drive tube. The pump-off test results showed that this device accurately detected cease of the blood pumps without being affected by the cardiac pulsation. These results suggest that this detecting device is feasible and useful as an external safeguard for the patients in whom the NIPRO-VAD is implanted.