A free-space optical communication apparatus comprising: an optical splitter for splitting modulated light into split light and a plurality of beams of signal light; a phase adjustment unit for adjusting a phase of each of the plurality of beams of signal light obtained by the optical splitter; an optical amplification unit for amplifying each of the plurality of beams of signal light obtained after phase adjustment by the phase adjustment unit; an optical phased array antenna for outputting each of the plurality of beams of signal light obtained after amplification by the optical amplification unit to space; a phase control unit (108, 109, 110, 111, 112) for synchronizing each of the plurality of beams of signal light with a reference signal by controlling the phase adjustment unit, each of the plurality of beams of signal light being output from the optical phased array antenna and multiplexed with the split light obtained from the optical splitter; an acquisition and tracking mechanism for adjusting an output angle of each of the plurality of beams of signal light output from the optical phased array antenna; an angle detection unit (114, 115) for detecting an angle of arrival of received light arriving from outside the apparatus; and a control unit (116, 117, 118) for setting the reference signal used in the phase control unit to a plurality of first reference signals having different frequencies for the individual beams of signal light, acquiring the received light by controlling the acquisition and tracking mechanism on a basis of a result of detection by the angle detection unit, setting the reference signal to a second reference signal having an equal frequency for each of the plurality of beams of signal light after acquisition is completed, and tracking the received light by controlling the phase adjustment unit on a basis of the result of detection by the angle detection unit, wherein when the control unit sets the reference signal used in the phase control unit to the plurality of first reference signals, the optical array antenna outputs a light obtained by incoherent beam combining and having a beam spread to space, as a beacon light, when the control unit sets the reference signal used in the phase control unit to the second reference signal, the optical array antenna outputs a light obtained by coherent beam combining and having a narrow beam size to space. an optical splitter for splitting modulated light into split light and a plurality of beams of signal light; a phase adjustment unit for adjusting a phase of each of the plurality of beams of signal light obtained by the optical splitter; an optical amplification unit for amplifying each of the plurality of beams of signal light obtained after phase adjustment by the phase adjustment unit; an optical phased array antenna for outputting each of the plurality of beams of signal light obtained after amplification by the optical amplification unit to space; a phase control unit (108, 109, 110, 111, 112) for synchronizing each of the plurality of beams of signal light with a reference signal by controlling the phase adjustment unit, each of the plurality of beams of signal light being output from the optical phased array antenna and multiplexed with the split light obtained from the optical splitter; an acquisition and tracking mechanism for adjusting an output angle of each of the plurality of beams of signal light output from the optical phased array antenna; an angle detection unit (114, 115) for detecting an angle of arrival of received light arriving from outside the apparatus; and a control unit (116, 117, 118) for setting the reference signal used in the phase control unit to a plurality of first reference signals having different frequencies for the individual beams of signal light, acquiring the received light by controlling the acquisition and tracking mechanism on a basis of a result of detection by the angle detection unit, setting the reference signal to a second reference signal having an equal frequency for each of the plurality of beams of signal light after acquisition is completed, and tracking the received light by controlling the phase adjustment unit on a basis of the result of detection by the angle detection unit, wherein when the control unit sets the reference signal used in the phase control unit to the plurality of first reference signals, the optical array antenna outputs a light obtained by incoherent beam combining and having a beam spread to space, as a beacon light, when the control unit sets the reference signal used in the phase control unit to the second reference signal, the optical array antenna outputs a light obtained by coherent beam combining and having a narrow beam size to space.