To release a medium securely from a fixed roll without damaging the medium. A releasing roller is disposed between a roll and a transport roller for nipping a medium and transporting the medium to a printing position. The releasing roller is rotated by a releasing motor so as to release the medium from the roll in a tangential direction of the roll. In addition, a sag part obtained by sagging the medium is formed between the releasing roller and the transport roller. A tension roller is placed on the sag part so that a constant tension is exerted on the released medium. A sag amount of the sag part is detected by monitoring a lower end part of the sag part with a sensor utilizing infrared rays. A printing apparatus releases the medium by the releasing roller to supply the medium so that the sag amount is within a predetermined range. The medium on which the constant tension is exerted is delivered by the transport roller onto a platen and is printed by a head.