A device for automatic replacement of the cloth beam (1) in a weaving loom, of the type in which the cloth beam (1) is supported and driven by a pair of driving cylinders (2,3) on which it rests, comprises a pair of cradle arms (6) for supporting a standby cloth roller (1R), automatic means for cutting the fabric, means (9,17) for guiding the edge of the cut fabric around said standby cloth roller (1R) and means for causing rotation of said roller (1R), said cradle arms (6) oscillating between a first position in which said standby roller (1R) is located alongside the cloth beam (1) and a second position in which said roller (1R) comes to rest on said driving cylinders (2,3).