An image forming apparatus includes a printing unit (PU) having a print head (2) for applying ink to a surface layer of a recording medium (1) transported thereto; a loop-forming unit (LU) capable of temporarily storing the recording medium (1) discharged from the printing unit (PU); and a heating unit (HU) for heating the recording medium fed from the loop-forming unit for fixing the ink applied to the surface layer onto its fixing layer. The heating unit (HU) includes a preliminary heating subunit (PR) for heating the recording medium from a normal temperature level to a ink fixing temperature level, a main heating unit (R) for heating the recording medium at the ink fixing temperature level and a slow cooling subunit (CU) for slowly cooling the recording medium to the normal temperature level. <IMAGE>
