NICT developed the world’s smallest and lightest quantum communication transmitter (SOTA) onboard the microsatellite SOCRATES. We succeeded in the demonstration of the first quantum communication experiment from space, receiving information from the satellite in a single-photon regime in an optical ground station in Koganei city. SOTA weighs 6 kg and its size is 17.8 cm length, 11.4 cm width and 26.8 cm height. It transmits a laser signal to the ground at a rate of 10 million bits per second from an altitude of 600 km at a speed of 7 km/s. We succeeded in correctly detecting the communication signal from SOTA moving at this fast speed. This is a major step toward building a global long-haul and truly secure satellite communication network.