PURPOSE: To structurally simply and inexpensively realize a large hybrid rocket having high thrust, and utilize its advantages without being accompanied by the use of non-efficient fuel and the low consumption rate.

CONSTITUTION: In a propellant injector for hybrid rockets, liquid component 1 flows in many fine tubes 2 across the inburned part of a solid component, and flows toward the burning surface of an internal burning system port 5. The tube originates from the outer surface of a solid fuel block 3 and extends into the port radially toward the port positioned in the center.