A vascular occlusion balloon catheter (2) of the present invention has a vascular occlusion balloon (10) elastically deformable and a shaft part having a main lumen (21) and a balloon expanding lumen (22). The balloon catheter (2) has an air discharge passage (7). The air discharge passage (7) has a distal end opening (71) located at a position distal from the balloon (10) and a proximal end communicates with an inner portion of the balloon (10). The distal end opening (71) of the air discharge passage (7) is positioned inside a portion disposed proximally from the distal end of the balloon catheter (2). The air discharge passage (7) communicates with the main lumen (21) at its distal end opening (71). The area of a cross section of the air discharge passage (7) orthogonal to an axial direction of the balloon catheter (2) is set to 200µm2 to 450µm2. The length of the air discharge passage 7 is set to 1.0 to 3.0mm.
