The polarizer of the present invention is a polarizer comprising a film having a structure having a minute domain dispersed in a matrix formed of a translucent thermoplastic resin including an absorption dichroic dye, wherein a transmittance to a linearly polarized light in a transmission direction is 80% or more, a haze value is 10% or less , and a haze value to a linearly polarized light in an absorption direction is 50% or more. The polarizer of the present invention is a dye-based polarizer having a high transmittance and a high polarization degree, capable of suppressing unevenness of transmittance in black display and excellent in reliability in heat resistance.