The growth of an attached cavity on a circular cylinder was calculated by the surface source distribution method. The singularity of the pressure at infinity due to the change of the cavity volume was removed by placing a sink on a circle of finite radius R surrounding the body. As R increased, the cavity growth was suppressed and the pressure rise on the solid surface increased. As an initial condition of the cavity growth, the pressure P on a body surface which was lower than the given cavity pressure P_c at non-cavitating condition, was assumed to incre se discontinuously to P_c at time t =0. Re-entrant jet was formed at the rear end of the cavity in one case, and the surface irregularity greatly increased in case the element size was halved. When the cavity hit the solid surface, a high pressure rise was obtained.