1. A living body information registration method executed by a computer, the method comprising: extracting vein data and characteristic amounts from a captured image which is living body information; and registering the extracted vein data and the extracted characteristic amounts, the characteristic amounts including: a first vein characteristic amount which is a frequency component obtained by characterizing periodicity of veins by performing a Fourier transform on a vein image obtained by reducing the vein data; a second vein characteristic amount which is an angle component obtained by characterizing a direction of a vein by performing a Fourier transform on the vein image; a third vein characteristic amount which is a curvature direction component obtained by characterizing a direction of a curvature of a vein of the vein image; a fourth vein characteristic amount which is a segment direction component obtained by characterizing a direction of a vein segment obtained by dividing a vein of the vein image; and a fifth vein characteristic amount which is a vein amount obtained by characterizing an amount of veins included in the vein image, wherein the fourth vein characteristic amount indicates distribution of segment direction components obtained by: dividing the vein image into a plurality of areas in accordance with a first division pattern; for each area, vectorizing the vein image, finding a vein segment made up of straight segments bent at vector points, calculating a slope of each segment, and drawing a histogram; dividing the vein image into a plurality of areas in accordance with a second division pattern that specifies different division positions from the first division pattern; and for each area obtained under the second division pattern, vectorizing the vein image, finding a vein segment made up of straight segments bent at vector points, calculating a slope of each segment, and drawing a histogram, and wherein the fifth vein characteristic amount indicates a distribution of vein amounts obtained by: dividing the vein image into a plurality of areas in accordance with the first division pattern; for each area, calculating the number of pixels corresponding to the veins included in the vein image and drawing a histogram; dividing the vein image into a plurality of areas in accordance with the second division pattern; and for each area obtained under the second division pattern, calculating the number of pixels corresponding to the veins included in the vein image and drawing a histogram.