This research proposes a set of devices called Bump Ahead which is able to express an uneven sensation to the user's finger and hand. Bump Ahead consists of two parts. One is a playmat that is made of a permanent magnet array and the other is a handheld device that equips a turntable with permanent magnets. By shifting the position of the magnet in the handheld device, Bump Ahead is able to switch the bumpy sensation on/off quickly. Thanks to the use of permanent magnets, this system is smaller and cheaper than those that use electric magnets for the same purpose. Also, users can arrange the magnet array to suit their requirements.