A node device of an optical ring network is disclosed. With the node device, a counterclockwise auxiliary wavelength supplied from a third switch part is returned and supplied to a clockwise add/drop part when there is a fault in an optical transmission path on a left side, a clockwise auxiliary wavelength supplied from a second switch part is returned and supplied to a counterclockwise add/drop part when there is a fault in an optical transmission path on a right side, a clockwise active wavelength supplied from a clockwise add/drop part is returned and supplied to a first switch part when there is a fault in the optical transmission path on the right side, and a counterclockwise active wavelength supplied from the counterclockwise add/drop part is returned and supplied to a fourth switch part when there is a fault in the optical transmission path on the left side.