To shorten the time required in restoration work when a plurality of different liquids are not exactly mixed.

In the mixing apparatus for many liquids, a drain valve 27 is provided to a static mixer 26 on the outlet side thereof. A control unit opens the outlet part on the side of a drain hose 30 of the drain valve 27 when it is judged that the amounts of both a main agent and a curing agent supplied to a premixer 19 are different from the amounts preliminarily calculated by operation, on the basis of the measuring results of flowmeters 21 and 22. Then, an on-off valve for the main agent and an on-off valve for the curing agent are alternately opened by operating a solenoid valve 17 to perform liquid supply operation until the sum total of the amounts of both the main agent and the curing agent supplied to the premixer 19 becomes at least the volume of the mixer 26. As a result, the mixed liquid in a mixing defective state within the premixer 19 is discharged from the drain valve 27.