To provide the subject device being simple in its structure and compact, injecting various materials together with a pressure medium into a combustion chamber of an engine, using no special seal for preventing the materials from being mixed, and being stable in operation.

This device includes a valve element 2 with a valve member 4 communicated with a combustion chamber of cylinder through nozzle orifices 6a, 6b at the opening position of a valve and closing a chamber 5 continuously supplied through supply ducts 8, 8a, a spring 7 acting to close the valve member 4, and a control valve 15 controlling injection of pressure medium. The valve element 2 includes a second chamber 12 whose pressure acts on the valve member 4 to be against the force of the spring 7. The rod 15 increases the pressure of the second chamber when the rod 15 moves to the opening position, and the member 4 is moved toward the combustion chamber of the cylinder to the position where injection can be made. In the case where pressure medium injected to the combustion cymber of the cylinder and presser medium of the control valve 15 are the same, e.g. water, the injection valve device can be more simplified and made more compact.