A suspension arm unit for vehicle includes: a pair of profile beams each having a U-shaped cross section with an opening oriented in a horizontal direction and including: a base end part formed on one end side of the profile beam and vertically swingably supported on a vehicle body side about an axis extending in a front-rear direction; and a distal end part formed on the other end side, to which a knuckle arm unit of a wheel is attached. The pair of the profile beams are arranged in the front-rear direction so that the openings face each other in the front-rear direction and a gap between the profile beams becomes larger from the distal end part to the base end part, and the pair of the profile beams are connected to each other at the distal end part and to the knuckle arm unit through a rotary joint.