To prevent the defect caused by the use of an ink cartridge of poor quality imitation by permitting the printing only in the case the reading result of a discrimination mark conforms to a preset discrimination mark in a printer with a discrimination mark read means.

An ink 20 to be used is a sheet-shaped ink stored in an exclusive ink cartridge 15, and reflection marks 30 (30a-30d) reflecting light are provided in the ink cartridge 15. When a reflective type photosensor is mounted on an ink cartridge storage section of a printer, the reflective type photosensor is set on the position in front of the reflection marks 30 to sense whether the reflection marks 30 are or not and also discriminate the existence of the ink cartridge 15 and the kind of the ink 20. Only in the case a pattern of the reflection marks 30 provided on the ink cartridge 15 is a pattern of specified kind, printing is permitted.