This invention relates to a polyvinyl alcohol type polarizing film or plate which comprises a water-soluble dye having the formula (1) in a free acid form or a copper complex salt thereof. The said polarizing plate has excellent polarizing performance capability and durability, and is suitably used for the green channel of a liquid crystal projector when B in formula (1) is a benzoylamino group and the water-soluble dye has a wave length for maximum absorption (.lamda.max) of 520 nm or more and less than 580 nm ##STR00001##