A drug dispensing apparatus including a cassette for containing drugs in an aligned state, a rotor disposed at one open end of the cassette, a pushing unit for pushing the drugs toward the rotor, a drive mechanism for pivoting the rotor alternately between a dispensing position and a receiving position by operating a drive switch to dispense the drugs one-by-one, and a measuring unit for measuring the present quantity of the drugs in the cassette. The apparatus also includes a memory unit for storing a stock quantity N0 of the drugs in the cassette. When the rotor is returned to the receiving position from the dispensing position, the present quantity N measured by the measuring unit is compared with the stock quantity N0 stored in the memory unit. If the present quantity N is less than the stock quantity N0, the present quantity N is stored in the memory unit as a stock quantity N0, while if the present quantity N is same as the stock quantity N0, it is informed that the drug has not been taken out.