PURPOSE: To connect an optical signal of an optional wavelength and an optional time slot to an optional outgoing line by converting an optical signal of a selected wavelength into an electric signal, moving the time slot and converting the electric signal into an optical signal of a prescribed wavelength.

CONSTITUTION: Multiplex optical signals 200, 210 are inputted to a variable wavelength selection element 120 via a branching device 110. When the variable wavelength selection element 120 selects an optical signal of a wavelength λ1, in a 1st time slot, an optical signal 220 is made incident in a photoelectric converter 130. Since the photoelectric converter 130 converts the optical signal 220 into an electric signal and the electric signal 230 is sent to a time switch 140. The time switch 140 shifts the signal A in the 1st time slot T1 of the electric signal 230 to a 2nd time slot T2 and sends an output electric signal 240 to a wavelength variable electrooptic converter 151. The wavelength variable electrooptic converter 151 converts the signal A of the 2nd time slot of the electric signal into a signal of a wavelength λ2 and sends the result to a confluent device 161.