An evaporated fuel treatment device includes a main adsorption chamber and a sub adsorption chamber. The sub adsorption chamber includes a first adsorption layer, a second adsorption layer and a high-desorption layer. The second adsorption layer is situated closer to an atmosphere port than the first adsorption layer is, and has a lower performance of adsorbing fuel vapor than the first adsorption layer does. The high-desorption layer is situated closer to the main adsorption chamber than the first adsorption layer is, and a higher performance of desorbing the fuel vapor than the first adsorption layer or the second adsorption layer does.