A seawater desalinization device includes a container portion, a guiding pipe, a plug, a heat conduction cover, a switch, and a connecting pipe. The container portion defines a receiving chamber, a slot, and a through hole communicating with the receiving chamber. The guiding pipe is fixed on the container portion to communicating with the slot. The plug is detachably inserted into the guiding pipe. The heat conduction cover covers on the container portion and sealing the receiving chamber and the slot. The switch is assembled in the container portion to control open or close the through hole upon a seawater level in the container portion. The connecting pipe is inserted into the through hole and a seawater source.