An information transmission system according to the present invention is constructed by connecting a transmission device which transmits information to an NC machine tool 20 via a network 2. The NC machine tool 20 comprises an operating panel 25 including an operation key 22, a keyboard 23, and a screen display section 24, and a control device 29 consisting of an input/output control section 40 which has a display control section 42. The display control section 42 receives information transmitted from the transmission device via the network 2, and display the same on the screen display section 24. Since the received information is automatically displayed on the screen display section 24 of the operating panel 25 being frequently looked at while an operator operates the NC machine tool 20, and that makes it possible to certainly give information to be given to the operator quickly and efficiently.