An optical switch is provided with: an optical matrix switch; and an optical path decision section which divides input light into two branches, supplies the input light of one divided branch to the optical matrix switch, demultiplexes the input light of the other divided branch into the light of individual wavelengths, subjects the demultiplexed optical signals to photoelectric conversion and generates electric signals corresponding to individual wavelengths, outputs connection request signals to SW connection request adjustment circuits for O1 to O4 which are set beforehand for individual wavelengths by receiving the generated electric signals, supplies, to the optical matrix switch, input port information JP corresponding to connection request transmitters from which the connection request signals are output, and decides optical paths in the optical matrix switch.