An optical space communications transmission and reception terminal that performs bidirectional communication with a paired optical space communications transmission and reception terminal having a same configuration as said optical space communications transmission and reception terminal, the optical space communications transmission and reception terminal comprising: an optical transceiver (2,2A) to convert transmission data into a transmission optical signal modulated at a symbol rate synchronized with a transmission clock signal and output the transmission optical signal, and generate received data by demodulating and decoding a signal obtained by sampling an input optical signal received from the paired optical space communications transmission and reception terminal at a cycle synchronized with a reception clock signal; a fiber coupling unit to output an intensity-modulated transmission optical signal as collimated light and couple the input optical signal to an optical fiber; an optical fiber amplifier to amplify the optical signal coupled to the optical fiber by the fiber coupling unit and output an amplified optical signal to the optical transceiver as a received optical signal; a tracking mirror to transmit the input optical signal to the fiber coupling unit, and output the intensity-modulated transmission optical signal collimated by the fiber coupling unit to space, in which a propagation angle is corrected on a basis of an input propagation angle error; a beam splitter to divide a part of an optical signal propagating between the tracking mirror and the fiber coupling unit; and an angle sensor to output the propagation angle error detected from the optical signal divided by the beam splitter to the tracking mirror, and output a clock signal extracted from the optical signal divided by the beam splitter to the optical transceiver as a reception clock signal, wherein the optical space communications transmission and reception terminal further comprises: an intensity modulation unit to generate the intensity-modulated transmission optical signal by superimposing a transmission clock signal on the transmission optical signal output from the optical transceiver and performing intensity modulation, and output the intensity-modulated transmission optical signal; and a transmission clock source to supply the transmission clock signal to both the optical transceiver and the intensity modulation unit. an optical transceiver (2,2A) to convert transmission data into a transmission optical signal modulated at a symbol rate synchronized with a transmission clock signal and output the transmission optical signal, and generate received data by demodulating and decoding a signal obtained by sampling an input optical signal received from the paired optical space communications transmission and reception terminal at a cycle synchronized with a reception clock signal; a fiber coupling unit to output an intensity-modulated transmission optical signal as collimated light and couple the input optical signal to an optical fiber; an optical fiber amplifier to amplify the optical signal coupled to the optical fiber by the fiber coupling unit and output an amplified optical signal to the optical transceiver as a received optical signal; a tracking mirror to transmit the input optical signal to the fiber coupling unit, and output the intensity-modulated transmission optical signal collimated by the fiber coupling unit to space, in which a propagation angle is corrected on a basis of an input propagation angle error; a beam splitter to divide a part of an optical signal propagating between the tracking mirror and the fiber coupling unit; and an angle sensor to output the propagation angle error detected from the optical signal divided by the beam splitter to the tracking mirror, and output a clock signal extracted from the optical signal divided by the beam splitter to the optical transceiver as a reception clock signal, wherein the optical space communications transmission and reception terminal further comprises: an intensity modulation unit to generate the intensity-modulated transmission optical signal by superimposing a transmission clock signal on the transmission optical signal output from the optical transceiver and performing intensity modulation, and output the intensity-modulated transmission optical signal; and a transmission clock source to supply the transmission clock signal to both the optical transceiver and the intensity modulation unit. an intensity modulation unit to generate the intensity-modulated transmission optical signal by superimposing a transmission clock signal on the transmission optical signal output from the optical transceiver and performing intensity modulation, and output the intensity-modulated transmission optical signal; and a transmission clock source to supply the transmission clock signal to both the optical transceiver and the intensity modulation unit.