PURPOSE: To provide a rigid and economical measuring device for additive and addition material which is continuously actuated to be synchronous with feed quantity of a spraying machine, and which can be steplessly controlled for all the spray mortar and concrete processes.

CONSTITUTION: A polished and adjusted rotor 2 having at least one rotor chamber 3 is used, an upper part and a lower part of the rotor 2 are surface- hardened, and it is sealed by a pair of polished slide bodies, that is seal plates 8, 10, especially, for example a solid body such as powder or grain is fed by air to be measured.