Disclosed is an apparatus for generating functional water which allows a container to be connected to a water bottle with an opening part which is standardized and available in the market, thus reducing water filled in the water bottle into functional water which is formed of oxygen water, sterilized and deodorized water, hydrogen or ionized water. The apparatus includes a container which accommodates a functional water generating member, wherein the upper and lower sides are blocked by an upper plate and a lower plate; and a water bottle connection part which is formed in the center of the upper plate while communicating with the inside of the container and is configured to connect separable the opening part of the water bottle.