A remote controller (15) includes a first balloon operation section (51), a second balloon operation section (52), a first balloon state display section (53), and a second balloon state display section (54). Each of the first and second balloon operation sections (51,52) performs a pressing operation to swell or contract a balloon. Each of the first and second balloon state display sections (53,54) has a swollen-state display portion (53A, 54A) and a contracted-state display portion (53B, 54B). The swollen-state display portion (53A,54A) is disposed along an outer circumference of each of the first and second balloon operation sections (51,52), such that the swollen-state display portion (53A,54A) and each of the first and second balloon operation sections (51,52) are coaxial with each other. The contracted-state display portion (53B, 54B) is disposed inside each of the first and second balloon operation sections (51,52), such that the contracted-state display portion (53B, 54B) and each of the first and second balloon operation sections (51,52) are coaxial with each other.
