Provided are an extended release preparation for oral administration of bosentan including bosentan, a pharmaceutically acceptable salt thereof or a solvate thereof as an active ingredient and a hydrophilic polymer as a sustained release excipient, and a method of manufacturing the same. Accordingly, the number of administrations of the bosentan, a pharmaceutically acceptable salt thereof or a solvate thereof may be reduced, thereby enhancing ease of administration and patient compliance. In addition, the extended release preparation for oral administration of bosentan may be effectively manufactured.
