To perform printing with high quality on a thick printing paper.

A carriage 20 in a head gap adjusting device supporting a printer head 30 is supported by a guide rail 11 and a carriage shaft 50 fixed to a chassis 10. A sub-carriage 20a holding the printer head 30 is fitted to a sliding groove formed on a face of a printer head side on the carriage 20. An outer circumference of a cam lever 23 having a cam forming shape provided on the side face of the sub-carriage 20a contacts a side face of the carriage 20. A compression spring 24 is disposed between a spring guide 25 formed on an upper portion of the carriage 20 and the sub-carriage 20a. When the cam lever 20 is rotated, its radius is lengthened, then the carriage 20 is urged and the printer head 30 is raised along with the sub-carriage 20a so that a head gap between a nozzle 31 and a printing paper 40 is enlarged.