Abstract: 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.