the objective of the present invention is to provide a vehicle door trim bonding device capable of quickly bonding sub - trims . in order to achieve the objective , the present invention provides a vehicle door trim bonding device for coupling a first sub - trim in which a projection is formed and which is made of a thermoplastic resin material , and a second sub - trim in which a receiving hole for receiving the projection of the first sub - trim is formed and which is made of a thermoplastic resin material , the device comprising : a heat supply unit for melting a part of the protrusion with radiation heat ; and a molding part for compression - molding the molten protrusion .