An object of the present invention is to provide a solid pharmaceutical composition which suppresses the characteristic bitter taste of 1-(3-(2-(1-benzothiophen-5-yl)ethoxy)propyl)azetidin-3-ol or a salt thereof and has a good storage stability of the-aforementioned compound or a salt thereof. The present invention provides a solid pharmaceutical composition comprising 1-(3-(2-(1-benzothiophen-5-yl)ethoxy)propyl)azetidin-3-ol or a salt thereof and a carboxylic acid whose solubility in water at 25°C is 50 g/100 g H<；sub>；2<；/sub>；O or less, wherein pH of a solution obtained when the solid pharmaceutical composition is dissolved or suspended in a 10 mmol/L KCl solution such that 1-(3-(2-(1-benzothiophen-5-yl)ethoxy)propyl)azetidin-3-ol or the salt thereof is 1 mg/mL or 8.96 mg/mL is 4.8 or less.
