To provide a compound which is useful as an active ingredient of a pharmacological composition for preventing or treating urine storage dysfunction, voiding dysfunction, lower urinary tract dysfunction, and the like. The present inventors have found that a thiazole derivative substituted with pyrazinylcarbonylamino at the 2-position is an excellent muscarinic M3 receptor-positive allosteric modulator and is expected as an agent for preventing or treating bladder/urinary tract diseases associated with bladder contraction via a muscarinic M3 receptor, thereby completing the present invention. 2-Acylaminothiazole derivative or a salt thereof of the present invention is expected as an agent for preventing or treating bladder/urinary diseases associated with bladder contractions via a muscarinic M3 receptor, for example voiding dysfunction such as underactive bladder.
