To provide a liquid charging nozzle which is easily used, low in the production cost, and suitable for dispensing a dose of variable volume of a highly viscous product.

In the liquid charging nozzle fitted to a vessel including the product, a variable volume type chamber is provided with a piston movable according to the pressure from the product between a first position of the maximum volume and a second position of the minimum volume so that the product is dispensed via a discharge port which is closed when the piston is at the first and second positions. The chamber is communicated with the vessel so that the product dispensed according to the movement has an invariable part in response to the difference between the maximum volume and a continuous part related to the operating condition of the product pressure to the piston.