Abstract: A device for attaching a front loader to a tractor by removably mounting each of a pair of boom supporting masts on a mast support fixed to the tractor body and removably fixing the front end of each brace extending forward from the mast to a brace fixing member secured to the front end of the tractor body. One of the lower end of each mast and the upper side of the mast support has a projection, and the other of these parts has a recessed portion for receiving the projection. The mast is pivotably supported by means of the projection and the recessed portion from below while being thereby restrained from moving longitudinally of the tractor body. A guide on the brace end and the fixing member coact to hold the brace end in position. The mast and the brace are fixed in position by a lockpin. The loader can be removably attached to the tractor with ease and high rigidity.