According to one embodiment, a marker generating method is provided. In the marker generating method, a value in a bit string is replaced with a signal pattern to generate a first signal pattern arrangement. The first signal pattern arrangement is divided into a first partial signal and a second partial signal. The first partial signal having a pattern cycle extended to a pattern cycle of the second partial signal is added to the second partial signal to generate a second signal pattern arrangement. A gradation of shading which indicates a signal of the second signal pattern arrangement is set.