Provided is an evaporated fuel treatment device configured to adsorb and desorb an evaporated fuel originating in a fuel tank. A first adsorption chamber is arranged in a flow passage. A second adsorption chamber is connected to the first adsorption chamber, and is arranged, in the flow passage, closer to an atmosphere port with respect to the first adsorption chamber. A first adsorption layer is arranged within the first adsorption chamber, and adsorbs the evaporated fuel. A second adsorption layer is arranged within the second adsorption chamber, and adsorbs the evaporated fuel. A sectional area of the second adsorption layer perpendicular to a direction in which the evaporated fuel flows through the second adsorption layer being larger than a sectional area of the first adsorption layer perpendicular to a direction in which the evaporated fuel flows through the first adsorption layer.