An optical transmission apparatus for performing optical transmission while dropping and adding optical signals with a plurality of wavelengths, comprising: an optical switching unit including an N × M wavelength selective switch with a plurality of N input ports and a plurality of M output ports, wherein N is three or more; an add controller configured to perform add control, wherein a plurality of add optical signals, which are optical signals to be added, have a plurality of k different bit rates, the add controller is connected to k input ports, out of the N input ports, and is arranged to send the add optical signals to the k input ports, wherein k is two or more, the number of add optical signals is more than k and less than or equal to N and the number of wavelengths of the add optical signals is more than k; and a drop controller connected to a plurality m of output ports out of the M output ports, where m is less than M, and the drop controller is arranged to perform drop control on optical signals sent from the m output ports; wherein k links connecting the k input ports of the N × M wavelength selective switch with the add controller have introduced therein dispersion compensators (14a, 14b) for compensating chromatic dispersions of the add optical signals with the respective bit rates, wherein the add controller is arranged to select the link through which each of the add optical signals is passed for dispersion compensation, and to send the add optical signals to the N × M wavelength selective switch via the selected links, and wherein the drop controller includes an m x 1 coupler with m inputs and one output, and a demultiplexer configured to demultiplex a drop optical signal output from the m x 1 coupler. an optical switching unit including an N × M wavelength selective switch with a plurality of N input ports and a plurality of M output ports, wherein N is three or more; an add controller configured to perform add control, wherein a plurality of add optical signals, which are optical signals to be added, have a plurality of k different bit rates, the add controller is connected to k input ports, out of the N input ports, and is arranged to send the add optical signals to the k input ports, wherein k is two or more, the number of add optical signals is more than k and less than or equal to N and the number of wavelengths of the add optical signals is more than k; and a drop controller connected to a plurality m of output ports out of the M output ports, where m is less than M, and the drop controller is arranged to perform drop control on optical signals sent from the m output ports; wherein k links connecting the k input ports of the N × M wavelength selective switch with the add controller have introduced therein dispersion compensators (14a, 14b) for compensating chromatic dispersions of the add optical signals with the respective bit rates, wherein the add controller is arranged to select the link through which each of the add optical signals is passed for dispersion compensation, and to send the add optical signals to the N × M wavelength selective switch via the selected links, and wherein the drop controller includes an m x 1 coupler with m inputs and one output, and a demultiplexer configured to demultiplex a drop optical signal output from the m x 1 coupler.