There is provided a drug injecting device including a drug feeding unit (110) feeding a drug (111a) to a surface of an object (200), an ultrasonic oscillating unit (120) oscillating an amplitude-modulated ultrasonic wave group in which amplitudes of respective ultrasonic waves are modulated, with respect to the surface of the object (200) fed with the drug (111a), and a control unit (130) controlling the amplitudes of the respective ultrasonic waves of the amplitude-modulated ultrasonic wave group oscillated from the ultrasonic oscillating unit (120) based on a drift velocity of the drug (111a) with respect to the object (200). Accordingly, when a drug is injected into a surface of an object such as a human body using ultrasonic waves, an effective injection according to the drug can be realized.