To provide a polarization plane holding type optical fiber grating which has few temperature variations in transmission loss properties for every polarized wave and of which productivity is improved with a simple configuration.

A first long-period type fiber grating 2 and a second long-period type fiber grating 3 have almost the same transmission loss properties. The polarization plane holding type optical fiber 1b to connect these two long-period type optical fiber gratings are fusion-bonded in the state of being twisted by 90 degrees so as to make the polarization plane different by 90 degrees. The optical fiber 1c connected to the output end of the second long-period type optical fiber grating 3 is also fusion-bonded in the state of being twisted by 90 degrees.