A heat dissipating device includes: a container body defining an inner space therein and having a fluid passage and opposite upper and lower walls; a working fluid received in the inner space in the container body; a wick structure mounted in the inner space; and a sealing material that seals the fluid passage of the container body. One of the upper and lower walls has a wall portion that is disposed adjacent to the fluid passage and that is depressed in such a manner that the depressed wall portion cooperates with the other of the upper and lower walls to form a sealing mechanism that functions to isolate the fluid passage from the inner space.