To provide a liquid mixing apparatus allowing injection of chemicals into a city water pipe with the chemicals uniformly agitated, when injecting chemicals separated with time.

In the liquid mixing apparatus 1 comprising a city water pipe 2 for running water, a liquid storage tank 4 storing chemicals 6 to be mixed into the city water pipe 2, and a liquid injection pipe 5 discharging the chemicals 6 discharged from the liquid storage tank 4 to the city water pipe 2, an agitation member 7 agitating the chemicals 6 stored in the liquid storage tank 4 and a drive mechanism 8 agitatingly driving the agitation member 7 in the liquid storage tank 4 are provided. A motor is used for the drive mechanism 8, and a mechanism agitating the agitation member 7 using the flow of a fluid flowing in the city water pipe 2 is used.