A machining program transmission system 1 has a control device of an NC machine tool 10, a transmission device 20 and a terminal device 40 are connected via an electrical communication line 2. The terminal device 40 reads an identification information 31 of a machining program, the identification information being attached to a medium 32. The terminal device 40 also reads an identification information 18 of the NC machine tool 10, the identification information being attached to the NC machine tool 10 for carrying out the machining. The terminal device 40 transmits the information to the transmission device 20. The transmission device 20 transmits the machining program corresponding to the program identification information 31 to the NC machine tool 10 corresponding to the machine identification information 18. The control device of the NC machine tool 10 receives and stores the machining program.