Crystal forms of (3R,4S)-7-hydroxymethyl-2,2,9-trimethyl-4-(phenethylamino)-3,4-dihydro-2H-pyrano[2,3-g]quinolin-3-ol that are excellent as a drug, and production methods thereof. Production methods include crystallizing (3R,4S)-7-hydroxymethyl-2,2,9-trimethyl-4-(phenethylamino)-3,4-dihydro-2H-pyrano[2,3-g]quinolin-3-ol from an acetate ester solvent, an aliphatic hydrocarbon solvent, a nitrile solvent, an aromatic hydrocarbon solvent, a ketone solvent or an ether solvent, and crystal forms obtained according to the methods.