To provide a compound capable of being industrially advantageously synthesized, having a reliable effect, and capable of especially being safely used to bring the compound to be stably formulated, and a harmful organism-controlling agent containing the compound as an active ingredient.

There is provided a crystal composed of a single diastereomer of an isoxazoline compound represented by formula (I). [In the formula, X represents a halogen atom or the like; n represents the number of substituent(s) of X; X' represents a halogen atom or the like; m represents the number of substituent(s) of X'; R¹ represents a 1-6C haloalkyl group; R² represents H or the like; R³ represents H, a substituted or non-substituted 1-6C alkyl group or the like; p represents a repeating number of the methylene group in the parenthesis and is an integer of 1 or 2].