PURPOSE: To eliminate the variation in the mixing ratio when supplying main agent having remarkably volume and viscosity larger than the main agent by providing the main agent supplying pipes radially at several places on the circumference of the main agent supplying parts.

CONSTITUTION: Several main agent supplyig pipes 10 are provided radially at the main agent supplying parts 9 extending on the upper streatm of the mising cylinder 1 and the main agent is divided and supplied to the main agent supplying parts 9. When the apparatus flow ratio of the main agent to the hardener flowing out of the dividing holes 8 of the hardener supplying pipes 7 is approached to 1:1, the premixing is conducted to eliminate the mixing variation between the main agent and the hardener caused by the non-uniform operation of the supply pump, differences in inertia and viscosity between the main agent and the hardener, etc.