Disclosed herein is a catheter apparatus for cranial cavities which exhibits the advantage of a conventional catheter structure in that a medicine and a bodily fluid are transferred along different paths, uniformizes the outer diameter of a catheter to easily use stereotactic equipment, and facilitates tunneling of the rear end of the catheter in a bypass space between the skull and the skin, so as to allow an operation to be simply and easily performed and thus to increase safety in operation. The catheter apparatus is advantageous in that no protrusion is formed on the outer surface of the catheter and thus the end of the catheter may be easily and accurately located in a cerebral ventricle using the stereotactic equipment, the catheter may be easily bent through the bypass space, and the rear end of the catheter may be easily exposed to the outside through a perforated part.