Calculations are presented which show the effect of resistivity in the expansion of a laser‐produced hot plasma against a magnetic field. Without resistivity, the expanding plasma has periodic behavior due to bouncing back from the field; but with resistivity, there is superimposed a slow diffusion (across the field) on the periodic oscillations. This is illustrated by considering a spherically symmetric plasma produced by a giant laser pulse (delivering power of the order of1010W) illuminating a particle of dimension10‐2cmand subsequently following the time development of its radius, skin‐depth, and temperature by integrating the nonlinear equations of motion and Ohm's law.