An assembly of a dash panel and a brake master cylinder unit of a vehicle disclosed herein may include: a panel-side support plate arranged between the brake master cylinder unit and the dash panel, the panel-side support plate being parallelly fixed to the dash panel; a unit-side support plate arranged between the dash panel and the panel-side support plate, the unit-side support plate being fixed to the brake master cylinder unit; a first anti-vibration plate interposed between the dash panel and the unit-side support plate; a second anti-vibration plate interposed between the unit-side support plate and the panel-side support plate; and a third anti-vibration plate interposed between the panel-side support plate and the brake master cylinder unit. A rigidity of the second anti-vibration plate in a plate thickness direction may be greater than any of rigidities of the first and the third anti-vibration plates in plate thickness directions.