Semiconductor laser assembly 1 is provided with semiconductor laser device 6 and heat dissipation member 24. Semiconductor laser device 6 includes semiconductor laser element 15, lead-frame 11, lower and upper enclosures 18 and 19 and plate-like spring 21 connected to lead-frame 11. Semiconductor laser element 15 is mounted on lead-frame 11 through sub-mounting member 16. Lower and upper enclosures 18 and 19 have an opening through which laser beams from semiconductor laser element 15 are emitted. Plate-like spring 21 is connected to lead-frame 11 and has wing and holding portions 22 and 23. Holding portion 23 is a C-character in cross section to put lower and upper enclosures 18 and 19 together. Heat dissipation member 24 has inside walls to define perforation 25, so that wing portions 22 of plate-like spring 21 pushes semiconductor laser device 6 against the inside walls of heat dissipation member 24 when the semiconductor laser device 6 is set in perforation 25.