Abstract: In a test method, an end of a testing optical fiber is first coupled to a light transmitting/receiving structure. The testing optical fiber and the light transmitting/receiving structure are then fixed, and the testing optical fiber is passed through the opening of a defining structure. Next, the testing optical fiber is moved within a testing zone defined by the opening, and variations of the strength of an optical signal transmitted in the testing optical fiber are measured. Finally, the quality of the light transmitting/receiving structure is judged according to the variations. The test apparatus includes the securing structure, the defining structure, and a testing structure.