An authentication image acquisition device for extracting a vein pattern and a palm print pattern from a single image comprising an authentication light source, a single authentication image acquisition unit, and an authentication image processing unit, wherein said authentication light source is configured for irradiating light that contains at least red light in the visible light region, toward a palm of human body, wherein said single authentication image acquisition unit is configured for obtaining at least one reflection color image to form by the light which is emitted from said authentication light source and is reflected on said palm of human body, wherein said at least one reflection color image has RGB pixel values in RGB color space or other color space that can be transformed to RGB color space, wherein said authentication image processing unit is configured for performing the image processing of said one reflection color image, and thereby extracting a palm print pattern and vein pattern in the palm respectively from said one reflection color image for authentication to conduct the processing to generate the authentication data, wherein, in said authentication image processing unit extracting the vein pattern is characterized in that it comprises: R signal and G signal on RGB color space or a signal equivalent to the R signal and a signal equivalent to the G signal on color space transformable for RGB color space of the reflection color image are transformed into R' signal and G' signal generated by transforming RGB color space or equivalent color space into HSV space, altering intensity of S signal on HSV space and transforming HSV space into RGB color space, M signal on CMYK color space or a signal equivalent to the M signal on color space transformable for CMYK color space of the reflection color image is transformed into M' signal generated by transforming RGB color space or equivalent color space into HSV space, altering phase of H signal and value of S signal on HSV space, and transforming HSV space into CMYK color space, and wherein said vein pattern is extracted from the data obtained by using either of the following formulae: GPvein = α 1 * R ′ + α 2 * M ′ − α 3 * G ′, or GPvein = α 1 * R ′ + α 2 * G ′ − α 3 * B ′ − α 4 * M ′, wherein α 1, α 2, and α 3, and α 4 are the experimentally determined coefficients; and B': The value obtained by transforming the value of B signal in RGB color space, or a signal equivalent to the B signal on color space transformable for RGB color space, into HSV space, altering the chroma and hue in HSV space and then bringing it back to RGB color system. R signal and G signal on RGB color space or a signal equivalent to the R signal and a signal equivalent to the G signal on color space transformable for RGB color space of the reflection color image are transformed into R' signal and G' signal generated by transforming RGB color space or equivalent color space into HSV space, altering intensity of S signal on HSV space and transforming HSV space into RGB color space, M signal on CMYK color space or a signal equivalent to the M signal on color space transformable for CMYK color space of the reflection color image is transformed into M' signal generated by transforming RGB color space or equivalent color space into HSV space, altering phase of H signal and value of S signal on HSV space, and transforming HSV space into CMYK color space, and wherein said vein pattern is extracted from the data obtained by using either of the following formulae: GPvein = α 1 * R ′ + α 2 * M ′ − α 3 * G ′, or GPvein = α 1 * R ′ + α 2 * G ′ − α 3 * B ′ − α 4 * M ′, wherein α 1, α 2, and α 3, and α 4 are the experimentally determined coefficients; and B': The value obtained by transforming the value of B signal in RGB color space, or a signal equivalent to the B signal on color space transformable for RGB color space, into HSV space, altering the chroma and hue in HSV space and then bringing it back to RGB color system. wherein α 1, α 2, and α 3, and α 4 are the experimentally determined coefficients; and B': The value obtained by transforming the value of B signal in RGB color space, or a signal equivalent to the B signal on color space transformable for RGB color space, into HSV space, altering the chroma and hue in HSV space and then bringing it back to RGB color system.