Abstract: [Object] To provide a high-quality, transparent garnet single crystal with suppressed cell growth that would otherwise lead to partially inhomogeneous crystal composition, and a method for producing the garnet single crystal. [Solving means] The garnet single crystal is grown by bringing a seed crystal into contact with a raw-material melt in a crucible disposed inside a chamber and pulling, while rotating, the seed crystal. The garnet single crystal is characterized by being represented by a general formula: (Tb3-xScx) (Sc2-yAly)Al3O12-z (provided that 0.11?x?0.14, and 0.17?y?0.23). The garnet single crystal is grown as follows. First, a mixture powder containing 20.9 to 21.2% by mole terbium oxide, 32.7 to 33.3% by mole scandium oxide, and the balance of aluminium oxide and unavoidable impurities is filled into the crucible and melted.