The application of Nd-Fe-B sintered magnets to the electronic parts has been greatly progressed and Nd-Fe-B sintered magnets are demanded to possess further excellent magnetic properties. Recently, Rubber Isostatic Pressing(RIP) method have been developed to get the high magnetic performance. Since in RIP, powders of the magnet inside rubber die are pressed like the isostatic process, the orientations of C axis of the powders don't change. Therefore, the magnet made by RIP shows superb magnetic properties. But, the effects of the RIP process conditions on the compactibility have not been clear because of the complicated behaviors of powders of the magnet and the rubber die in magnetic field. From obtained results through this study, it has been proved that the problems of RIP method are the bad compactibility such as the occurrence of the cracking and marked deviation in outer dia. of the RIP green compact although Nd-Fe-B sintered magnets made by RIP showed excellent magnetic properties.