To provide an apparatus for controlling an ink layer capable of simply controlling an ink layer thickness on an inking roller in a short time and reducing occurrence of a spoilage and a printer.

An offset lithographic printer comprises a special purpose detecting roller 9 for detecting an ink absorbance to contact with the inking roller 5, and an ink absorbance detector having a light emitting element 10 and a photodetector 11 and provided near a surface of the roller 9. The apparatus for controlling the ink layer thickness calculates the ink thickness on the roller 5 based on the absorbance detected by the detector and controls an ink amount on the roller 5 based on the calculated ink thickness.