Abstract: The present invention is concerned with an atomizer usable in both normal and inverted orientations, in which only the liquid to be atomized is sucked up into a pressurizing chamber 7 of a pump mechanism, while completely avoiding the flow of air into the pressurizing chamber, in both the normal and inverted orientations. The sucking of only the liquid is achieved by use of a suction passage 15 for operation in the inverted orientation provided in an ordinary pump mechanism 2, the suction passage 15 being opened at its one end to the pressurizing chamber and at its other end to a space outside and above the pump mechanism, and a stop valve 13A disposed in the suction passage 15 and adapted to open when the vacuum in the pressurizing chamber has been increased beyond a predetermined level, in the operation in inverted orientation.