An optical fiber connecting tool is provided in which an optical fiber connecting tool 5 is used which has a ferule 7, a connecting structure 10 which has two clamping sections 18, 19 which are disposed in a ferule 7. A pre-installed optical fiber 6 and a newly installed optical fiber 17 are clamped in a butt-connected condition by a clamping section 18. The newly installed optical fiber 17 is clamped by the other clamping section 19. An optical fiber connecting tool 1 is provided which has an open/close member 2 which is detachably disposed on the clamping section 18 and another open/close member 3 which is detachably disposed on the another clamping section 19 such that the both of the open/close members 2, 3 can be operated independently. Also, a method for connecting optical fibers according to the present invention prevents an increase in a loss due to a bent optical fiber and a damage in the optical fiber by extracting the open/close member 2 from the clamping section 18 before extracting the open/close member 3 from the another clamping section and dispose a deformation which is generated on the tip section of the optical fiber when the optical fiber connecting part is attached on the tip section of the optical fiber according to steps for performing an extracting operation for the open/close member e from the another clamping section. Here, for the optical fiber connecting part, for example, various members can be adapted such as a member which does not have the above explained ferule, and a member which realize a connection and a clamping operation for the optical fibers by a structure of only the above explained connecting structure.