A printing apparatus includes a printing medium support unit supporting a printing medium supplied to a print execution area and guiding the transported printing medium. The printing medium support unit includes a support portion supporting the printing medium and defining a predetermined gap between a print head and the support portion. A suction hole disposed in a width direction of the printing medium adsorbs and supports the printing medium on the support portion by applying a suction force to the printing medium. A first recess portion with an ink discharge port is disposed at a position corresponding to a position at an edge of the printing medium of a size which is supposed to be used and receives ink possibly discarded upon executing marginless printing. A first communication passage applies some of the suction force to the first recess portion in a passage independent from the ink discharge port.