A belt molding structure for motor vehicles includes a molding body including a resiliently-deformable anti-vibration lip which is integrally formed on an inner surface of the molding body; an end cap attachable to an end of the molding body, and including an insertion portion; a lip-escape space, provided inside the molding body so as not to interfere with the insertion portion of the end cap, for allowing at least a portion of the anti-vibration lip to come into the lip-escape space when the anti-vibration lip is deformed; and a deforming guide surface formed on the end cap in a vicinity of an insertion end of the insertion portion to resiliently deform the anti-vibration lip into the lip-escape space when the insertion portion is inserted into the molding body.