Elastic (Young, shear and bulk moduli, Poisson's ratio and Lamé parameter), longitudinal and transverse internal friction values for low carbon steel and stainless steel were simultaneously measured over a temperature range 300-1500 K, by an ultrasonic pulse sing-around method. These elastic moduli decrease and Poisson's ratio increases with increasing temperature, suggesting activation of shear mode in a high temperature region. Longitudinal and transverse internal frictions are sensitive to recrystalization, and to α(ferritic)/γ(austenitic) phase transition and solution of precipitated carbide phases into the austenitic matrix, respectively. A relaxation peak with an apparent activation energy of 0.97 eV was observed at around 610 K for the carbon steel.