To provide a convenient method for determining the residual quantity of ink surely.

At least a liquid agent containing section and a liquid agent supply section having outlet side sealed hermetically with a resilient member are provided. The resilient member is bored by means of a liquid agent introducing member in order to use the liquid agent. While supplying ink to an imaging means from a box type ink cartridge being fixed externally, a detecting means provided on the side of the liquid agent containing section detects the fact that the mass of ink in the cartridge has reached a specified value.