We developed a ridge filter that enables to adjust the dose distribution in a spread out Bragg peak of proton beam by remote control. This device has 4 blocks a block of which is a quarter of a conical shape of MiX-DP block. Each pair of two blocks is put on an each line perpendicularly intersecting each other. The intersecting point of these two lines is coincided with an axis of proton beam. We could flatten the dose distribution of spread out Bragg peak of proton beam by adjusting the distance between two blocks of each pair. We, moreover, can adjust it if necessary, for example, in a case that relative biological effectiveness in spread out Bragg peak increases with depth.