Polarizer having non-polarization portions, a long polarizing plate and image display device comprising the polarizer

A polarizer, comprising a resin film containing a dichromatic substance, the polarizer having a thickness of 10 μm or less,

• wherein when the polarizer is applied to an image display apparatus, a non-polarization portion having a substantially circular shape as a plan-view shape is arranged at a position corresponding to a camera portion of the image display apparatus,
• wherein the non-polarization portion includes a recessed portion having a recessed surface on one surface side of the resin film,
• wherein a step difference between the non-polarization portion and any other portions is 1 μm or less,
• wherein the content of the dichromatic substance in the non-polarization portion is 0.2 wt % or less, and
• wherein a content of an alkali metal, an alkaline earth metal or the alkali metal and the alkaline earth metal in the non-polarization portion is 3.6 wt % or less.