This invention is directed to an ameliorating agent for a disease based on vesicourethral dyssynergia, comprising, as an active ingredient, 3-(15-hydroxypentadecyl)-2,4,4-trimethyl-2-cyclohexene-1-one, a salt thereof, or a solvate thereof. The disease based on vesicourethral dyssynergia is any of dysuria accompanying a lifestyle-related disease (such as diabetic dysuria), idiopathic dysuria, dysuria after pelvic surgery, dysuria accompanying spinal cord injury, dysuria accompanying spinal canal stenosis, dysuria accompanying benign prostatic hypertrophy, dysuria accompanying high-pressure voiding/high-pressure urine storage, neurogenic or nonneurogenic lower urinary tract symptoms (LUTS), detrusor sphincter dyssynergia, and detrusor bladder neck dyssynergia.