According to one implementation, an optical observation system includes an optical fiber and at least one detection system. The optical fiber has at least one curved portion as a sensor for inputting light which has occurred in a test region. The optical fiber inputs the light from the at least one curved portion and transmits the light. The at least one detection system detects the light transmitted by the optical fiber. Further, according to one implementation, an optical observation method includes: inputting light, which has occurred in a test region, from at least one curved portion of an optical fiber and transmitting the light; and detecting the light transmitted by the optical fiber.