In this paper we investigate the eigen values and principal directions of the energy-momentum tensor of the ferrofluid. The model we are concerned with, was proposed and introduced by Cattaneo and Cissoko. That energy-momentum tensor is not symmetric and it is not positive that eigen values are real. We obtain four different eigen values. Two eigen values are real and corresponding principal directions are space-like. For other two eigen values we find the condition making them real. We analyze the conditions determining the type of the corresponding principal direction.