Abstract: This invention provides a dispensing device for toilet tank. It dispenses a liquid cleanser substantially in a predetermined quantity during each flushing cycle. The dispensing device comprises a float and a container disposed adjacently under the float for holding the cleanser; a dispensing member fitted in the outlet of the container, which includes vertical and transverse passage defining tortuous passages for discharging a substantially measured liquid cleanser when the dispensing device is automatically pivoting to an inverted position relative to its normally mounting position caused by a decrease of buoyance in a flushing cycle, and will restore to the normally mounting position when the water level rises again.