Several types of implementation of panel loudspeakers, for example, distributed mode loudspeaker(DML), are proposed. The diaphragm of DML is thought as behave like a bending plate. The diaphragm of an electrostatic loudspeaker is thought move as a rigid plate. What is the difference of an acoustical sound field generation feature with each implementation ? In this paper, we used models of same dimensional rectangular panel. One is a rigid diaphragm. Another is a bending panel that has an actuator in the center of it. We made simulations of directivity and sound pressure distribution in a rectangular room. We could show less coherent SPL distribution in the case of bending panel.