An optical communication device whereby optical attenuation characteristics are linearized to suppress optical level variations among wavelengths attributable to the attenuation characteristics and thereby enable long-distance transmission. Optical attenuators attenuate optical signals of respective wavelengths in accordance with optical attenuation data output from a control data converter. An optical multiplexer multiplexes the optical signals, and an optical amplifier amplifies the multiplexed signal. A control data output unit outputs optical signal control data based on differences between a set optical level and the optical levels of respective wavelengths input to the optical amplifier. A data table holds data for converting the optical signal control data to the optical attenuation data so that the optical attenuation amounts of the attenuators may be linearized with respect to the optical signal control data. A control data converter looks up the data table to convert the optical signal control data to the optical attenuation data.