Mechanically fastened joints are common method of connecting structural components in aerospace structures. Bearing failure is the main failure mode at these portions of quasi-isotropic composite structures. Therefore, it is required for improving the reliability of structural health monitoring technique from the present techniques [1] to detect bearing failures including micro-damages. In this paper, micro-damages are defined as the fiber micro-buckling, matrix cracking, interlaminar delamination and out-of-plane shear cracking. The bearing damage tests were conducted to develop the damage detection method using the BOCDA optical fiber sensors. In these tests, optical fiber sensors were the hole-assisted-fiber and its diameter is 125 um. In order to understand the relationship between the BOCDA measurement results and damages, several specimens were observed by means of optical microscopy. The BOCDA can detect micro-damages by comparing the measuring results after damaged with that before damaged.