a housing having inner surfaces forming an evaporation space, and having an outer surface contacting with a heat source, the housing being connected to a working fluid inlet pipe on one side and a vapor outlet pipe on another side thereof, and configured to fill a working fluid with a level therein;

a wick installed on an inner surface corresponding to the heat source among the inner surfaces to generate movement of the working fluid by capillary action;

a partition wall dividing the evaporation space into a plurality of spaces communicating with each other and supporting the wick; and

a distributor installed extending to an opposite side of the working fluid inlet pipe to mix the working fluid introduced through the working fluid inlet pipe with the working fluid pre-filled in the evaporation space,

wherein the partition wall includes a partition wall body part having a band shape and a communication part formed in the partition wall body part, and the vapor flows between the plurality of spaces partitioned by the partition wall through the communication part.