We propose multiwavelength in-line phase-shifting digital holography with a monochrome image sensor, single reference arm, and no mechanical scanning. We use phase-shifting interferometry selectively extracting wavelength information as a method to obtain multiwavelength object waves separately from wavelength-multiplexed phase-shifted holograms. By exploiting a liquid crystal on silicon spatial light modulator with a wide phase-modulation range as an electrically driven phase shifter in this interferometry, we remove mechanically moving parts during phase shifting. Its effectiveness is experimentally demonstrated.