Provided is a polarizer with excellent durability and an image display device including the polarizer. The polarizer includes a composition for forming a polarizer which contains a polymer liquid crystal compound and a dichroic material, in which the dichroic material includes a first dichroic material and a second dichroic material, an absolute value of a difference between a log P value of the first dichroic material and a log P value of the second dichroic material is 1.0 or less, and a stabilization energy indicating an energy loss in a case where one dichroic material of the first dichroic material and the second dichroic material is incorporated into a structure singly formed of the other dichroic material that is aligned therein is 30 kcal/mol or less.