In an optical semiconductor device module constructed by an optical semiconductor device having a light emitting portion on its top surface, a mounting substrate adapted to mount the optical semiconductor device thereon, and at least one conductive leaf spring adapted to fix the optical semiconductor device to the mounting substrate and supply power to the optical semiconductor device, the leaf spring is formed by a plurality of rectangularly-shaped terminals, and natural frequencies of at least two of the rectangularly-shaped terminals are different from each other.