To examine the basic characteristics of reconnection of the dayside magnetopause, we have numerically studied the reconnection process at an interface where the total pressure is in balance but where the thermal pressure is higher on one side than on the other. Reconnection is caused by anomalous resistivity that is assumed to operate only in a localized region at the interface. Boundaries are assumed to be free boundaries, but reflection of the perturbations originating from inside the simulation region is suppressed by placement of an absorbing region. Results can be expressed as follows, denoting the high-pressure and low-pressure regions as magnetosheath and magnetosphere, respectively. (1) a slow shock is formed in magnetosheath and a slow expansion fan is formed in magnetosphere; (2) at the slow shock the Lorentz force and pressure gradient are of comparable importance in accelerating plasma, but at the expansion fan the pressure gradient has the dominant effect, and (3) the acceleration depends on the direction of the interplanetary magnetic field (IMF) and when the reconnection line is assumed to be directed at the half angle (&thgr;/2) between IMF and geomagnetic field, the velocity of the accelerated plasma is roughly proportional to sin2(&thgr;/2)+sin3(&thgr;/2).