A catheter apparatus for percutaneous coronary intervention (PCI) capable of accurately positioning the balloon and stent in a desired position includes an introducer set fixed to an opening of the human artery, a guiding catheter secured to the introducer set and introduced into the artery, a Y-connector coupled with the guiding catheter, a guidewire introduced into the guiding catheter, a balloon catheter introduced into the guiding catheter and having a balloon at the distal end thereof, a minute adjustment portion having a nut and a bolt for minutely adjusting the insertion portion of the balloon catheter in the artery, a combining frame having two legs eachcoupled with the main tube and the nut, respectively, and a clamping portion for holding the balloon catheter firmly in position. The catheter apparatus provided by the present invention helps the physician to place the balloon and stent more accurately in the desired position of the artery so that the PCI operation becomes more accurate, easier and safer.