The present invention provides: a controlled release oral preparation comprising bosentan as an active ingredient, a pharmaceutically acceptable salt thereof, or a hydrophilic polymer as a solvate thereof, and an extended release material; a method for preparing the controlled release oral preparation. It is possible to reduce the administration time of the bosentan, acceptable salt thereof, or a solvate thereof, thereby improving convenience and compliance. Furthermore, a bosentan controlled release oral preparation can be effectively prepared by the present invention.