A tractor includes a mounting plate, a protruding tube, a boom supporter, and a boom. The mounting plate is attachable to a frame on a side surface of a vehicle. The protruding tube is connected to the mounting plate, and shaped to protrude from a portion in which the protruding tube is connected to the mounting plate, toward the outside of the vehicle. The boom supporter is connected to a distal end portion of the protruding tube, and shaped to protrude upward from a portion in which the boom supporter is connected to the distal end portion of the protruding tube. The boom is coupled to the boom supporter via a boom coupler, and formed to extend from the boom coupler toward the front side of the vehicle. In a side view, an imaginary straight line extending vertically downward from the boom coupler is located rearward of the protruding tube.