To make the size of a semiconductor laser module having an optical isolator smaller, its assembly easier and its cost lower.

The semiconductor laser module has a semiconductor laser element 101, a condenser lens 102 and an optical fiber holder 104 for supporting the end of an optical fiber 103 within the module and has the optical isolator 105 consisting of a first polarizer 106, a second polarizer 107 and a Faraday rotator 108 for preventing the reflection return from the optical fiber 103 to the semiconductor laser element 101. The semiconductor laser element 101 and the first polarizer 106 are fixed and supported to a mount block 111 and the second polarizer 107 and the Faraday rotator 108 are internally supported to the optical fiber holder 104. If the mount block 111 and the optical fiber holder 104 are assembled to the module in assembling the semiconductor laser module, the first and second polarizers 106 and 107 and the Faraday rotator 108 are eventually simultaneously assembled, by which the assembly work is simplified and the semiconductor laser module of the small size may be provided at the lower cost.