An optical packet transmitter device includes: a detection unit for detecting packet-length information and priority information from a received Ether signal; a setting unit for setting, according to the degree of priority, a division factor by which the Ether signal is divided and a wavelength used for an optical packet signal to be transmitted; a header generation unit for generating a header containing destination information, the packet-length information, the priority information, and information of wavelength in use of the Ether signal; a transmission processing unit for dividing the Ether signal according to the set division factor and generating a plurality of packet signals; a header insertion unit for inserting the generated header in at least one packet signal; and an electrical/optical converter unit for converting the plurality of packet signals into optical packet signals of a plurality of wavelengths according to the set wavelength in use.