This balloon catheter system is equipped with: a catheter shaft (1) that comprises an outer tubular shaft (2) and an inner tubular shaft (3) that can slide with respect to each other and an expandable balloon (6) that is provided between the tip (4) of the outer tubular shaft (2) and a vicinity of the tip (5) of the inner tubular shaft (3). The balloon catheter system has a structure wherein a fluid supply path (9) that connects to the inside of the balloon (6) is formed between the outer tubular shaft (2) and the inner tubular shaft (3), a handle section (11) is provided with a front tank (12) and a rear tank (13) that are connected together through a connecting tube (15), the front and rear tanks (12, 13) and the inner tubular shaft (3) that passes through the centers of the tanks are allowed to slide with respect to each other, stopcocks (22, 32) serving as gaskets for fluid leakage prevention are provided at parts where the inner tubular shaft (3) slides with respect to the front and rear tanks (12, 13), the front and rear tanks (12, 13) are connected to the inside of the balloon (6) through the fluid supply path (9), and an internal piston (27) is provided in front of the rear tank (13), such that the internal pressures of the front and rear tanks (12, 13) are changed as the inner tubular shaft (3) that is fixed to the center part of the piston is moved in the front-rear direction. The balloon catheter system is configured such that when the inner tubular shaft (3) is pushed forward, the balloon (6) is stretched, and the balloon (6) contracts as a negative pressure is created inside the rear tank (13), whereas when the inner tubular shaft (3) is pulled back rearward, the balloon (6) is released from being stretched, and the balloon (6) expands as a positive pressure is created inside the rear tank (13).La présente invention concerne un système de cathéter à ballonnet doté de : une tige de cathéter (1) qui comprend une tige tubulaire externe (2) et une tige tubu
