Achromatic polarizing plate with high-transmissivity and high-degree of polarization

A polarizing element, comprising an azo compound represented by formula (1) or a salt thereof and an azo compound represented by formula (2) or a salt thereof, wherein the absolute value of the difference between the average transmittance at 420 nm to 480 nm and the average transmittance at 520 nm to 590 nm is equal to or less than 2.5%, and the absolute value of the difference between the average transmittance at 520 nm to 590 nm and the average transmittance at 590 nm to 640 nm is equal to or less than 2.0% , wherein each wavelength transmittance is obtained using two of said polarizing elements in which their absorption axes are positioned in parallel:

• wherein A1 represents a phenyl group or a naphthyl group having a substituent, R1 to R4 each independently represent any of a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group, X1 represents an amino group that may have a substituent, and k represents an integer of 0 or 1;
• and
• wherein A2 and A3 each independently represent a naphthyl group or a phenyl group having one or more substituents, at least one of the substituents is a sulfo group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group, and R5 and R6 each independently represent any of a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group.