We developed a new type of compact magnetic force booster by which we succeeded in crystallizing proteins (hen egg white lysozyme) while making them levitate in a solution without contacting the container. This technique is noteworthy in the practical merit that we could control the growth of crystals from the initial stage of nucleation merely in a magnetic field of a few Tesla. The shape of the booster was designed in accordance with the dynamical stability against external forces acting on the crystals. Under a stable condition, the crystals condensed spherically, and formed a “shell shaped” crystallization with a hollow interior. Our magnetic force booster has the potential for innovation, especially in the field of protein crystal engineering.