To provide a method capable of highly accurately positioning-adjusting and fixing an optical fiber on an device in which the optical fiber can be fitted.

A holding member 6a of the optical fiber 6 has an outermost face made of a metal of the same kind as that of the outermost face of the fixing face 12 provided on the device, and is suitable for an adjustment member 5 including a fitting face 32 extending in the direction perpendicular to the optical axis of the optical fiber. Fine particles 8 made of the same kind of metallic material as that of the outermost face of the fixing face and the fitting face are applied on the fixing face 12 of the device to form a fine particle layer 9, the fitting face 32 of the adjustment member 5 is pressed against the fixing face 12 on which the fine particle layer is formed, the adjustment member 5 is moved in the direction intersecting at right angle with the optical axis of the optical fiber while keeping pressed, the position of the optical fiber 6 in the device is adjusted, and after finishing the position adjustment, the fine particle layer 9 is heated and pressurized to connect the fixing face 12 and the fitting face 32.