<p>The present invention provides a fiber Bragg grating element which is simply configured and capable of obtaining a high cut-off amount exceeding 40 dB in a wide range. A fiber Bragg grating element of the present invention has a plurality of gratings formed in an optical waveguide having a core and a cladding around the core thereby to perform high rejection filtering on an input optical signal over a desired bandwidth, the gratings being formed with a grating pitch between adjacent two of the gratings increasing toward a center in a longitudinal direction of the optical waveguide.</p>
