To provide a boom conveyor for a self-unloader vessel which can allow short-period vertical motion to be absorbed by a chute without causing external dust scattering or chute durability deterioration.

A boom conveyor 2A for a self-unloader vessel is used in such a manner that a chute 3A is inserted into a receiving hopper 100 and bulks are unloaded while continuously introducing them. The chute 3A has a double structure configured with an inner chute 30 and an outer chute 39. The inner chute 30 includes metallic joint members 31, 32, 33, 34, 35 that are in a bottom-free washbowl form with the upper end side being larger in diameter than the lower end side while allowing vertical stretching motion through a stretching mechanism and that are so provided consecutively as to form a vertically stretchable concertina form. The outer chute 39 includes a concertina elastic resin bellows that covers the outer periphery of the inner chute 30 without space. The inner periphery of the inner chute 30 constitutes a metallic bulk introduction path and the outer chute 39 constitutes a resin-made powdery material scattering preventive means in such a way that both can perform stretching motion integrally.