A thermal printer in which a thermal head can be attached easily to a print unit without requiring a tool such as a screw driver.The thermal printer has a printing unit (40) having a left ribbon frame (43) and a right ribbon frame (42) facing each other. A head housing (60) is attached between the frames (42, 43) while supporting a thermal head (12). A supporting-recess in the surface of the left ribbon frame (43) faces the right ribbon frame (42) and supporting the left side face (64) of the head housing (60). A frame cover (70) is fitted on and removed from a fitting portion provided on the outer surface of the right ribbon frame which is at the back side of the surface facing the left ribbon frame (43) and the cover supporting a right side face (62) of the head housing (60) through a through-hole (50a) formed on the right ribbon frame (42).