PURPOSE: To perform continuous mixing of material components at a mixing ratio given in advance in a single mixing chamber and to enable arbitrary setting of the value of the mixing ratio within a prescribed range.

CONSTITUTION: First, by a first dosing pump 3 actuated by first fluid pressure and for conveying a first material component, the first material component is conveyed into a mixer. Furthermore, by a second dosing pump 3' actuated by second fluid pressure and for conveying a second material component, the second material component is conveyed into the mixer. Subsequently, the mixture finished by the mixer is fed to a consumption promoting appliance. On the other hand, flow rate measured values 30, 30' of flows discharged by both dosing pumps 30, 30' are inputted to a controller 5, and the second dosing pump 3' is independently controlled by the controller 5 so that the ratio of the first to the second material component in the mixture is adjusted to a value set as an object value in advance.