The present invention provides a catheter 100 having a structure wherein an electronic component 2 is mounted on the anterior end or an intermediate part of a tube 1, a signal line electrically connecting to the electronic component 2 extends from the vicinity of the electronic component 2 through the aforementioned tube 1 to the posterior end of the aforementioned tube 1, which is characterized in that the signal line consists of a wiring pattern 4 of the flexible printed circuit board 10 inserted in the tube 1. Consequently, an electronic component-loaded catheter can control increase in the size of the tube caused by multiple signal lines to be connected to the electronic component.