To provide a low-cost, small-sized, and low-PDL optical variable attenuator array for WDM.

This optical variable attenuator has such a structure that: a plurality of resin optical waveguides are formed on an electrode formed on a substrate; a graded type multi-mode waveguide is formed on the waveguides; a groove is formed in the multi-mode waveguide; and the refractive indexes of the waveguides are adjudged by heating liquid crystal injected into the groove while simultaneously applying voltage by the electrode at right angles to a propagation direction of light.