To provide a thermal transfer printer which has a separation plate capable of being easily curved with a high degree of curving accuracy, and an assembly method for the thermal transfer printer.

This thermal transfer printer is equipped with a long platen roller 2, a long thermal head 3 which is arranged in a direction parallel to the longitudinal direction of the platen roller 2, recording paper 5 and an ink ribbon 6, which are carried to positions between the platen roller 2 and the thermal head 3, and the separation plate 9 which can separate the ink ribbon 6, serving for printing, from the recording paper 5 by using the thermal head 3. The separation plate 9 is arranged on a downstream side with respect to the thermal head 13 in the carrying direction, shown by an arrow B, of the paper 5 during printing; a spacer 5 is arranged between the separation plate 9 and the thermal head; and the separation plate 9 is formed in a curved shape via the spacer 5 so that a width-direction central part of the ink ribbon 6 can be set most protruded.