[Problem] To provide a drug injection device and a drug injection method which are capable of increasing drug injection efficiency at deep parts of a solid organ such as the brain and of improving therapeutic effects for pathological changes that require a drug injection into the deep parts of a solid organ such as the brain. [Solution] A long and narrow insertion body (11) with a solid interior is provided such that a tip (11a) thereof is capable of being inserted into a solid organ of a patient. The insertion body (11) has a groove (11b) on a side thereof along the longitudinal direction. An ultrasonic wave generation unit (12) comprises: an oscillator (21) which vibrates ultrasonically and an oscillation transmission member (22) which connects the oscillator (21) and the insertion body (11) so as to transmit ultrasonic vibration of the oscillator (21) to the insertion body (11) and which is formed such that the outer diameter thereof tapers from one end part that is in contact with the oscillator (21) toward another end part that is in contact with the insertion body (11). A tube (13) is provided so as to be capable of discharging the drug into the patients solid organ from a tip. The tip of the tube (13) is inserted into the groove (11b) of the insertion body (11).Le problème décrit par la présente invention est de pourvoir à un dispositif dinjection de médicament ainsi quà une méthode dinjection de médicament permettant daccroître lefficacité dinjection de médicament au niveau de parties profondes dun organe solide tel que le cerveau, et daméliorer les effets thérapeutiques pour des changements pathologiques requérant une injection de médicament dans les parties profondes dun organe solide tel que le cerveau. La solution selon linvention porte sur un corps dinsertion (11) long et étroit doté dun intérieur solide et conçu de sorte que son extrémité (11a) puisse être introduite dans un organe solide dun patient. Le corps dinsertion (11) comporte une rainure (11b)
