The present invention provides an oral preparation sufficiently masking the bitter taste of pioglitazone and a salt thereof. The present invention provides an oral preparation containing pioglitazone or a salt thereof and alkali metal chloride.本發明提供一種可充分地掩蓋皮利酮(pioglitazone)及其鹽的苦味之口服製劑。本發明提供含有皮利酮或其鹽與鹼金屬氯化物之口服製劑。