A measurement apparatus includes: a measurement tank including an air inlet and an air outlet; a fan; a light source configured to irradiate micro-particulate matter with light; a photodetector configured to detect scattered light from the micro-particulate matter; a first circuit configured to detect individual particles of the micro-particulate matter based on an output of the photodetector; a second circuit configured to detect a micro-particle group of the micro-particulate matter based on the output of the photodetector; a switch configured to switch into one of a first state in which the output of the photodetector is input to the first circuit and a second state in which the output of the photodetector is input to the second circuit; and a controller configured to control a drive and stop of the fan, a turn-on and a turn-off of the light source, and a switching of a state of the switch.