PROBLEM TO BE SOLVED: To provide a drug administration catheter capable of delivering a drug to a lesion site without leaking it at all and effectively administering the drug while expanding the lesion site firmly. A drug administration catheter (10) has an elongated catheter body (20) having an expansion lumen (23) through which a fluid can flow, and a balloon (30) arranged on the distal end side of the catheter body (20). A first balloon portion 50 capable of forming a first space 56 communicating with the dilation lumen 23 between the catheter body 20 and the first balloon portion 50 is arranged so as to cover the first balloon portion 50, and a first balloon portion 50 is provided between the first balloon portion 50 and the first balloon portion 50. The second balloon portion 60 capable of forming the two spaces 66 is provided, and the first balloon portion 50 opens the first space 56 and the second space 66 by an increase in internal pressure due to the fluid at the time of expansion. The second balloon portion 60 has a portion 59, and the second balloon portion 60 is formed with pores 67 capable of discharging the fluid to the outside of the second balloon portion 60. [Selection diagram] Fig. 4【課題】病変部まで薬剤を全く漏出させずに搬送でき、かつ病変部をしっかりと拡張させつつ薬剤を効果的に投与できる薬剤投与カテーテルを提供する。【解決手段】薬剤投与カテーテル１０は、流体を流通可能な拡張ルーメン２３を備える長尺のカテーテル本体２０と、カテーテル本体２０の先端側に配置されるバルーン３０と、を有し、バルーン３０は、カテーテル本体２０との間に拡張ルーメン２３と連通する第１空間５６を形成可能な第１バルーン部５０と、第１バルーン部５０を覆うように配置され、第１バルーン部５０との間に第２空間６６を形成可能な第２バルーン部６０と、を有し、第１バルーン部５０は、拡張時の流体による内部圧力の上昇によって、第１空間５６と第２空間６６とが開通する開通部５９を有し、第２バルーン部６０は、流体を第２バルーン部６０の外部へ放出可能な細孔６７が形成される。【選択図】図４
