A water activation device efficiently activates water and maintains its activation performance over a long period of time. The water activation device includes a conductive body having an in-flow opening and an out-flow opening, a cover member that coats the outer perimeter of the body through insulation material and is insulated from water pipes, a plurality of holders overlapped with one another in an axial direction of the body, and a plurality of activation material units each being formed in a cylindrical block containing minerals as a main component. The activation material units are held in a retainer of the holder without contacting with one another. Each of the holders is formed of a retainer having a plurality of flow openings.