PROBLEM TO BE SOLVED: To provide an optical measurement system capable of observing a blood flow change that appears in a time zone before and after the start time of a task period, in the region of interest in the brain of a subject.SOLUTION: An optical measurement system 1 includes: a light transmission/reception part 30 having N pieces of light transmission probes 12 and M pieces of light reception probes 13； and control parts 21 and 22 for obtaining measurement data related to the time change of brain activity in the wide range of the brain of the subject, by controlling the transmission and reception of light for the light transmission/reception part 30 using a wide range control table. The system includes a selection means 24 for storing, in a storage part 23, a narrow range control table for irradiating the subject with light in order using Y pieces of light transmission probes 12, and the control parts 21 and 22 can obtain the measurement data related to the time change of the brain activity in the narrow range of the brain of the subject by controlling the transmission and reception of the light for the light transmission/reception part 30 using the narrow range control table after the narrow range control table is stored in the selection means 24.
