A study on the measuring and evaluation of LSC(Least Square Center) roundness was carried out. The experimental set-up was made by index head and indicator, and the measuring data were compensated by a developed computer program. The results obtained are as follows : 1) An index head can conveniently be used to measure LSC roundness. 2) A program for calculating LSC roundness is developed. 3) Without a high quality roundnes measuring apparatus, LSC roundness can be measured and calculated by using index head and the developed program in machine shop as well as in a measuring room