Provided is a digital watermark detecting device for improving the accuracy of reliability judgment of detected information thereby to prevent misdetection. The digital watermark detecting device includes a pixel extracting unit (107) for extracting pixels embedded as a digital watermark from an input image to output an extracted pixel value row, an orthogonal pattern generating unit (102) for generating all orthogonal patterns belonging to a set of patterns orthogonal to one another, a detecting unit (103) for calculating a correlation by using the integration result of each of the orthogonal patterns and the extracted pixel value row, to determine the detected values corresponding to the respective orthogonal patterns and a standard deviation for detected values excluding a maximum detected value with a maximum absolute value from the calculated respective detected values, thereby to calculate a reliability discrimination parameter value given as the quotient obtained by dividing the maximum detected value by the standard deviation, a reliability discriminating unit (104) for outputting information corresponding to the result of comparison between a threshold parameter and the reliability discrimination parameter value, and a detected-information converting unit (105) for converting the detected value inputted from the detecting unit into predetermined information, when the reliability of the detected values satisfies a standard, and for outputting the predetermined information.