A small-sized dehumidifier having a humidifying function. The dehumidifier (1) has a fan (2), a heater (32), an adsorption element (31), a second fan (33), and a heat exchange section (35). The adsorption element (31) has a disc shape outline and adsorbs moisture in air flowing by action of the fan (2). The second fan (33) applies high temperature air produced by the heater (32) to a part of the adsorption element (31) to make the element release the moisture. The heat exchange section (35) is installed in an outer peripheral space located radially outside the adsorption element (31) and condenses moisture contained in the high temperature air having passed through the adsorption element (31).; Because the heat exchange section (35) is installed in the outer peripheral space outside the adsorption element (31), an increase in the dimension of the device in the direction of air flow is minimized and, in addition, the heat exchange section (35) has sufficient effective area.