In magnetic crystals belonging to chiral space groups, the crystallographic chirality affects the arrangement of spin magnetic moments. The crystallographic symmetry plays a role of a “mold” which pins down the spatial arrangement of the spins. Consequently, in this category of magnetic crystals it becomes possible to control such abstract quantities as the spin chirality or the phase of the spin’s wave function. Based on these ideas, we review our recent progress on chiral magnetic crystals.