A thermal printer includes a thermal head which has heating elements arranged in a main scanning direction, a transport unit for transporting a thermal recording material in a sub scanning direction perpendicular to the main scanning direction and a skewing unit for skewing the thermal recording material so that its ends in the main scanning direction form an angle with respect to the sub scanning direction at a predetermined recording position. The thermal recording material that has been skewed so that its ends form the angle is supplied to the recording position, and the thermal recording on the thermal recording material is performed with the thermal head while the thermal recording material that remains skewed is transported in the sub scanning direction.