PURPOSE: To obtain an improved quality paving asphalt even from a low quality asphalt precursor material without a performance-enhancing agent by catalytically oxidizing an asphalt precursor, and subsequently mixing a sufficient amount of the catalytically oxidized asphalt cement with the asphalt precursor.

CONSTITUTION: In the first step, a high quality paving asphalt precursor, a low quality paving asphalt precursor, a non-paving asphalt precursor or a mixture thereof is catalytically oxidized with FeCl3, etc., as a catalyst at a temperature of 232°C to form a paving asphalt cement, and in the second step, the catalytically oxidized paving asphalt cement is mixed with one or more high quality paving asphalt precursors, a low quality paving asphalt precursor, a non-paving asphalt precursor or a mixture thereof to prepare a paving asphalt cement of the desired grade to obtain the objective quality-improved paving asphalt free of a performance-enhancing agent.