A watermark information embedding device, comprising: a color component separation unit for separating an original image of a two-dimensional code into color components; a first wavelet transform unit for performing, for each of the color components separated by the color component separation unit, a wavelet transform on the original image of the two-dimensional code to decompose this image into various frequency components; a watermark information embedding unit for embedding watermark information, as a high-frequency component in the oblique direction, in a high-frequency component in the oblique direction of the each of the color components out of the various frequency components decomposed by the first wavelet transform unit; an inverse wavelet transform unit recomposing the two-dimensional code containing watermark information by performing an inverse wavelet transform on frequency components other than the high-frequency component in the oblique direction, out of the various frequency components decomposed by the first wavelet transform unit, and the high-frequency component in the oblique direction in which the watermark information is embedded by the watermark information embedding unit; and a color component integration unit for integrating the two-dimensional code containing watermark information for the each color component recomposed by the inverse wavelet transform unit; characterized in that the watermark information embedding unit executes embedding of the watermark information for a wavelet coefficient obtained through the wavelet transform, and when the wavelet coefficient in the high-frequency component in the oblique direction of the original image of the two-dimensional code after the wavelet transform has been executed (j+1) times by the first wavelet transform unit is w m,n ^(j+1,d) (where (m,n) is the position of the pixel and d is an index indicating that the wavelet coefficient is a coefficient of a high-frequency component in an oblique direction), the watermark binary image is T m,n, the color weighting coefficient is α and the embedding strength is bit, the wavelet coefficient W m,n ^(j+1,d) of the two-dimensional code containing watermark information is expressed by the following formula. W m, n j + 1, d = { w m, n j + 1, d + bit × α if T m, n = 0 BLACK w m, n j + 1, d otherwise a color component separation unit for separating an original image of a two-dimensional code into color components; a first wavelet transform unit for performing, for each of the color components separated by the color component separation unit, a wavelet transform on the original image of the two-dimensional code to decompose this image into various frequency components; a watermark information embedding unit for embedding watermark information, as a high-frequency component in the oblique direction, in a high-frequency component in the oblique direction of the each of the color components out of the various frequency components decomposed by the first wavelet transform unit; an inverse wavelet transform unit recomposing the two-dimensional code containing watermark information by performing an inverse wavelet transform on frequency components other than the high-frequency component in the oblique direction, out of the various frequency components decomposed by the first wavelet transform unit, and the high-frequency component in the oblique direction in which the watermark information is embedded by the watermark information embedding unit; and a color component integration unit for integrating the two-dimensional code containing watermark information for the each color component recomposed by the inverse wavelet transform unit;