To provide a water purifying device easy in maintenance, preferably improving water quality with simple structure, made compact or having good operability, or a water purifying device preventing electrical parts from being submerged, and a water-ozone mixing device.

Provision of an operation display part 55, an ozone generating device 21, an ozone mixer 7 and a control part 49 in a casing 27 allows operation, control and action to be performed in a places related to the casing 27, allowing easy maintenance and making the device compact. Operation of a pump 5 and the ozone generating device 21 are interlockingly controlled by the control part 49 based on water pressure of the delivery side of the pump 5, which enhances operability. The electrical parts like the ozone generating device 21 and control part 49 are located above a water channel 87 and isolated from the water channel 87 by a shielding wall 80, so that the electrical parts can be surely prevented from being submerged.