The data of the pressure calibration of a quadrupole mass spectrometer ATLASAMP 3 for six gases: N_2, Ar, H_2, O_2, CH_4 and H_2O are presented. Two kinds of commercially available ionization gauges were served in the calibration system, there are Bayard-Alpert type Balzers IM 15-52 U and Varian UHV-24. A capacitance manometer Baratron can be used as a first standard gauge. The data of calibration of Balzers IM 15—52 U against Baratron gauge and extrapolation of the data can be used as a secondary standard ...