To provide a water supply device and a steam generation device capable of preventing the overspill of water without removing a water supply tank.

The water supply device includes a water tank part in which water is stored; an accommodation part which is detachably placed inside the water tank and in which consumable goods that need replenishment are accommodated; a water supply part which has a water supply opening and supplies water to the water tank part via the water supply opening in order to keep the water level of the water tank part constant; a valve body which is provided at the water supply opening and always energized in the closing direction of the water supply opening and which opens its valve based on the applied pressing force. The water supply device is also provided with an opening part which is provided at a device body in order to attach/detach the accommodation part at the time of replenishing consumable goods to/from the water supply device a lid body which is mounted at the opening part to disable the attachment/detachment of the accommodation part; and a pressing force member which is supported in the vicinity of the water supply opening, which applies a pressing force by bringing an end part into contact with the valve body to open the valve of the valve body when the lid body is mounted, and which separates the end part from the valve body when the lid body is not mounted.