This invention relates to a tablet containing, as an active ingredient, 7-[4-(4-benzo[b]thiophen-4-yl -piperazin-1-yl)butoxy]-1H-quinolin-2-one or a salt thereof, that has excellent disintegration ability, storage stability and photostability.The tablet of the present invention comprising an uncoated tablet containing 7-[4-(4-benzo[b]thiophen-4 -yl-piperazin-1-yl)butoxy]-1H-quinolin-2-one or a salt thereof as an active ingredient, excipients such as lactose, corn starch, and microcrystalline cellulose; disintegrants such as low-substituted hydroxypropylcellulose, croscarmellose sodium, and sodium carboxymethyl starch; binders such as hydroxypropylcellulose; lubricants such as stearate; and further comprising a coating layer, containing hypromellose; talc; titanium oxide; colorant; and the like, the coating layer being applied to the surface of the uncoated tablet.