An optical fiber device (1) includes an upper cover (18), a lower cover (19), and two optical fiber holders (2). Each optical fiber holder includes a retaining body (10), a strain relief boot (20), and an interconnection member (30). A passage is defined in each optical fiber holder, for receiving a plurality of optical fibers therethrough. An inner rib (311) is formed on an inner surface of the interconnection member, and is engagingly received in a groove (112) defined in a front portion of the retaining body. Two parallel outer ribs (321) are formed on an outer surface of the interconnection member, and are engagingly received in corresponding grooves (162) defined in the upper and lower covers. An engaging bead (211) is formed at a front end of the strain relief boot, and is engagingly received in a rear groove (123) defined in an intermediate portion of the retaining body.