Gases that were desorbed from ball bearings were measured in ultrahigh vacuum of about 1×10−10Torr. Test bearings have the following characteristics: (1) No plated parts, (2) Ag or Pb ion plated balls, (3) MoS2sputtered balls, (4) TiN (plasma chemical vapor deposition)+Ag (ion plating) dual‐coated inner and outer rings, and Ag ion plated balls. Two test bearings supported a stainless‐steel rotor in ultrahigh vacuum, and were loaded axially at 98 N. They were driven by magnetic coupling at 140 rpm. Variations in the pressure and the partial pressure of each gas were caused by desorption from the bearings only. From test results, it was found that Ag or Pb ion plated bearings could be used in ultrahigh vacuum. These bearings settled down to a nondesorbing state in a short rotation time. The rotation time was about 11 h for Ag ion plated bearings, and about 17 h for Pb ion plated bearings. H2, CH4, H2O, CO, N2, CO2, and Ar were the main components of the desorbed gases during rotation.