The invention provides a polarized light irradiation device with wire grating polarization element. When the device is mantained, the grid is prevented from damages caused by touch of finger on the grid forming surface of the wire grating polarization element installed on the device or falling of article. The grid forming surfaces of the wire grating polarization element are equipped towards one side of the light source. Moreover, a filter for covering the grid forming surface is equipped above the grid forming surface (between the polarization and the light source). The filter is used for the light which is needed to be polarized to penetrate.