Inhaler

An inhaler comprising:

• a housing having one surface, an other surface opposite to the one surface, and a plurality of side surfaces connecting the one surface and the other surface;
• a mouthpiece which is disposed on the one surface of the housing;
• a reservoir which is disposed inside the housing and stores an inhalable composition;
• a nozzle which extends from the reservoir towards the mouthpiece;
• a needle valve which is movably disposed inside the nozzle;
• a piston which has one surface coupled to the needle valve, and vertically reciprocates in a first direction from the other surface to the one surface of the housing or a second direction from the one surface of the housing to the other surface of the housing;
• and
• a spring which is provided below the piston in a preloaded state,
• wherein, when a suction force is not applied to the mouthpiece, the needle valve is maintained in a first state in which the nozzle is closed,
• wherein, when the suction force is applied through the mouthpiece, the needle valve is switched into a second state in which the nozzle is opened,
• wherein, when the suction force is not applied to the mouthpiece, the spring pushes the piston up in the first direction to maintain the first state, and
• wherein, when the suction force is applied through the mouthpiece, the piston overcomes preload of the spring and moves in the second direction to switch into the second state.