A digital watermark detecting device includes an extracting unit to extract pixels embedded as a digital watermark from an input image and to output an extracted pixel value row, a generating unit to generate a set of orthogonal patterns, a detecting unit to calculate a correlation using an integration result of the orthogonal patterns and the extracted pixel value row, to determine detected values corresponding to the orthogonal patterns and a standard deviation for detected values excluding a maximum detected value with a maximum absolute value from the calculated detected values, to calculate a quotient by dividing the maximum detected value by the standard deviation, a discriminating unit to output information corresponding to the result of comparison between a threshold parameter and the quotient, and a unit to convert the detected value inputted from the detecting unit into predetermined information, when the reliability of the detected values satisfies a standard.