Provided are a medicine ejection device capable of realizing appropriate ejection by surely setting an inner pressure of a medicine tank at a negative pressure in an initial period of every ejection time, and a control method for the medicine ejection device. A medicine container section that contains medicine is coupled to a medicine ejection section including nozzles from which the medicine is ejected, and elements which generate energy for ejecting the medicine from the nozzles. A plug as a movable wall positionally shifts so that a capacity of the medicine container section can increase or decrease in accordance with a predetermined pressure difference between an inside and outside of the medicine container section. Prior to opening a head cap, the capacity is increased so as to generate pressure variations in a negative pressure direction, which have a larger value than a value equivalent to the predetermined pressure difference.
