In order to investigate the fundamental behavior of thermal stress ratchetting, strain controlled push-pull low-cycle fatigue tests with steady torsional stress were conducted on ASTM A302-B steel, AISI 304 steel, and JIS SCM 3 steel under constant elevated and cyclic temperatures. The test results are summarized as follows: (1) Torsional ratchet deformation gradually increased as a permanent deformation fluctuating as axial strain changed. The amplitude of the fluctuation depends on cyclic axial strain, but permanent deformation depends on steady stress as well as cyclic axial strain. (2) Ratchet strain increased at a nearly constant rate for each cycle of axial strain. The rate of increase is proportional to steady torsional stress and exponentially proportional to the axial strain amplitude. (3) The torsional stress and deformation caused by the tests do not influence low cycle fatigue or thermal-fatigue strength.