The invention relates to a medical instrument used for drug absorption of pulmonary alveoli, in particular to an intrapulmonary drug administration device atomizing drugs dissolved in liquid into fine particles reaching the pulmonary alveoli, which comprises a casing and a suction nozzle arranged at one side of the casing. The invention is characterized in that a battery, a liquid supplying bottle and an atomizer are arranged in the casing, wherein, one end of the liquid supplying bottle is communicated with the suction nozzle, while the other end is connected with the atomizer, an air inlet is arranged on the casing above the atomizer, and an air passage is arranged on the outer surface of the liquid supplying bottle; an action switch is arranged on the casing. The invention has the advantages that the drug can be atomized into uniform particles, the particles are small, and the average diameter can reach about 1 micron, which is the best technical parameter for intrapulmonary absorption; a quantitative device arranged in the invention can control the drug administration amount; the invention can be used for drug administration of bronchioles and pulmonary alveoli.