  We propose a possible mechanism of the charge stripe order due to the
next-nearest neighbor exchange interaction J' in the two-dimensional t-J model,
based on the concept of the phase separation. We also calculate some hole
correlation functions of the finite cluster of the model using the numerical
diagonalization, to examine the realization of the mechanism. It is also found
that the next-nearest neighbor hopping t' suppresses the stripe order induced
by the present mechanism for t'<0, while it enhances for t'>0.
