To provide a liquid supply device employing a magnet pump capable of supplying liquid without an overload on the magnet pump even in a small amount of discharge flow.

The liquid supply device is provided with a tank 11 for reserving liquid L, a magnet pump 2, a shower head 4 through which the liquid L is discharged, a supply piping 6 for connecting the tank 1 with the magnet pump 2, a discharge piping 7 for connecting the magnet pump 2 with the shower head 4 and a circulation piping 8 branched off from the discharge piping 7 to be connected with the tank 1. By adjusting liquid flow to the circulation piping 8, the liquid flow through the shower head 4 can be adjusted with the discharge amount of the magnet pump 2 kept constant.