A venting device (100,200) configured to be provided at one side of a battery cell or a battery module and configured to discharge gas in the battery cell or the battery module to an outside, the venting device (100,200) comprising: a gas inlet (110,210) configured to allow gas in the battery cell or the battery module to be introduced therethrough; a gas outlet (120,220) configured to allow the gas introduced through the gas inlet (110,210) to be discharged to the outside therethrough; a connection portion (140,240) configured to connect the gas inlet (110,210) and the gas outlet (120,220) to each other; and a sealing cap (130,230) located in the connection portion (140,240), the sealing cap (130,230) being configured to automatically discharge gas to the outside, wherein the sealing cap (130,230) blocks connection between the gas inlet (110,210) and the gas outlet (120,220), thereby blocking discharge of gas and introduction of external air, in a normal state, and moves in the connection portion (140,240) under a predetermined condition such that the gas inlet (110,210) and the gas outlet (120,220) are connected to each other wherein, in use, when an internal temperature is increased to a predetermined level or higher due to gas generated in the battery cell or the battery module, the sealing cap moves in the connection portion such that the gas inlet and the gas outlet are connected to each other, characterized in that an alarm means (150, 250) is provided at one side of the gas outlet (120, 220), the alarm means (150, 250) being configured to generate a sound when the gas is discharged to the outside, and in that the connection portion is made of a heat shrink tube configured to shrink at a predetermined temperature or higher. a gas inlet (110,210) configured to allow gas in the battery cell or the battery module to be introduced therethrough; a gas outlet (120,220) configured to allow the gas introduced through the gas inlet (110,210) to be discharged to the outside therethrough; a connection portion (140,240) configured to connect the gas inlet (110,210) and the gas outlet (120,220) to each other; and a sealing cap (130,230) located in the connection portion (140,240), the sealing cap (130,230) being configured to automatically discharge gas to the outside, wherein the sealing cap (130,230) blocks connection between the gas inlet (110,210) and the gas outlet (120,220), thereby blocking discharge of gas and introduction of external air, in a normal state, and moves in the connection portion (140,240) under a predetermined condition such that the gas inlet (110,210) and the gas outlet (120,220) are connected to each other wherein, in use, when an internal temperature is increased to a predetermined level or higher due to gas generated in the battery cell or the battery module, the sealing cap moves in the connection portion such that the gas inlet and the gas outlet are connected to each other, characterized in that an alarm means (150, 250) is provided at one side of the gas outlet (120, 220), the alarm means (150, 250) being configured to generate a sound when the gas is discharged to the outside, and in that the connection portion is made of a heat shrink tube configured to shrink at a predetermined temperature or higher.