This invention provides a nasal device for use while breathing and adapted for insertion within a human nasal cavity, the device comprising: a main body being tubular in shape having a hollow structure which extends from the end of front side to the end of rear side; a front opening portion and a rear opening portion; wherein the hollow structure is in a shape that the rear side becomes narrower towards the front side having a smaller diameter. The nasal device in this invention is easy to carry, which can be placed inside nasal cavity to bring sufficient air into the respiratory tract.