A method for preparing a crystal of
4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carbamoyl]benzo-
ic acid having a single endothermic peak approximately at 233.degree. C.
in differential scanning calorimetry, which comprises the step of
recrystallizing a crystal of
4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carbamoyl]benzo-
ic acid from a mixture of water and ethanol. The method enables selective
preparation of type-II crystals which are stable against physical impact.
The resulting crystals are free from highly toxic hexane as a residual
solvent, and preferably used as an active ingredient of pharmaceuticals.