By measuring the magneto capacitance spectroscopy of an n type InSb metal insulator semiconductor (MIS) structure, the 2 dimensional hole subband in the p type channel of the InSb MIS device was investigated under different magnetic fields at 1 2K.It was shown that the on set energy of the p type channel has a strong dependence on the magnetic field. This behavior has been attributed mainly to the dependence of the InSb band gap energy on magnetic field.