<；P>；PROBLEM TO BE SOLVED: To provide a catheter which exactly measures blood pressure in proper timing, and has measurement accuracy not varying over time to stably measure the blood pressure. <；P>；SOLUTION: The catheter has: a sensor 40 for measuring pressure using light； an optical fiber 33 which is connected to the sensor 40 and extends in the axial direction； a gel-like substance filled in the surroundings of the sensor 40； a surrounding wall 37 which partitions the surroundings of a filling space 38 of the gel-like substance； a distal end partition wall 39 which closes the distal end of the filling space 38 so as to partition the outside where the pressure should be measured and the filling space 38 and has flexibility； and a highly rigid rear end partition wall 35 which closes the rear end of the filling space 38. <；P>；COPYRIGHT: (C)2011,JPO&INPIT
