A 3D image display optical member comprising: an image generating unit having first modulated-light generating areas to optically modulate linearly-polarized light having a first polarizing axis with a predetermined angle based on a first image signal thereby generating first modulation-polarization light for emission and second modulated-light generating areas to optically modulate the linearly-polarized light having the first polarizing axis based on a second image signal thereby generating second modulation-polarization light for emission; a polarizing plate configured to transmit and emit the first modulation-polarization light and the second modulation-polarization light emitted from the image generating unit, as first modulation-polarization light and second modulation-polarization light as linearly polarized light having a second polarizing axis different from the first polarizing axis; and a polarizing-axis control plate having first polarization areas arranged corresponding to the position of the first modulated-light generating areas in the image generating unit to change a polarizing axis of the first modulation-polarization light, which has been emitted from the polarizing plate and entered the first polarization areas, to a third polarizing axis thereby generating a third modulation-polarization light for emission, second polarization areas arranged corresponding to the position of the second modulated-light generating areas in the image generating unit to change a polarizing axis of the second modulation-polarization light, which has been emitted from the polarizing plate and entered the second polarization area, to a fourth polarizing axis thereby generating a fourth modulation-polarization light for emission, wherein the image generating unit has image generating area shading parts each arranged at a boundary between one of the first modulated-light generating areas and one of the second modulated-light generating areas to shade incident light, wherein the polarizing-axis control plate has shading parts each arranged at a boundary between one of the first polarization areas and one of the second polarization areas to shade incident light, and wherein each shading part of the polarizing-axis control plate is formed so as to contain a plurality of straight lines each having a width smaller than the linewidth of the image generating area shading part. an image generating unit having first modulated-light generating areas to optically modulate linearly-polarized light having a first polarizing axis with a predetermined angle based on a first image signal thereby generating first modulation-polarization light for emission and second modulated-light generating areas to optically modulate the linearly-polarized light having the first polarizing axis based on a second image signal thereby generating second modulation-polarization light for emission; a polarizing plate configured to transmit and emit the first modulation-polarization light and the second modulation-polarization light emitted from the image generating unit, as first modulation-polarization light and second modulation-polarization light as linearly polarized light having a second polarizing axis different from the first polarizing axis; and a polarizing-axis control plate having first polarization areas arranged corresponding to the position of the first modulated-light generating areas in the image generating unit to change a polarizing axis of the first modulation-polarization light, which has been emitted from the polarizing plate and entered the first polarization areas, to a third polarizing axis thereby generating a third modulation-polarization light for emission, second polarization areas arranged corresponding to the position of the second modulated-light generating areas in the image generating unit to change a polarizing axis of the second modulation-polarization light, which has been emitted from the polarizing plate and entered the second polarization area, to a fourth polarizing axis thereby generating a fourth modulation-polarization light for emission, wherein the image generating unit has image generating area shading parts each arranged at a boundary between one of the first modulated-light generating areas and one of the second modulated-light generating areas to shade incident light, wherein the polarizing-axis control plate has shading parts each arranged at a boundary between one of the first polarization areas and one of the second polarization areas to shade incident light, and wherein each shading part of the polarizing-axis control plate is formed so as to contain a plurality of straight lines each having a width smaller than the linewidth of the image generating area shading part.