To prevent the generation of stop mark at the restart of a loom by accurately adjusting the fabric mouth position after weft mending.

The apparatus 10 for fabric mouth position adjustment has either one or both of independently installed dedicated winding motor 23 to drive a surface roll 22 and dedicated delivery motor 15 to drive a warp beam 4. When the apparatus has either one of the motors, the motor is driven independent of the main shaft 26 of the loom 1 based on the rotation command during the stop of the loom 1 or, when the apparatus have both motors, either one or both of the motors are driven in the same manner. The apparatus is further provided with a manual operation device 40 to generate the rotation command by manual operation and a drive controlling device 33 driving the dedicated motors 15, 23 independent of the main shaft 26 at a rotation amount corresponding to one pick including the value after the decimal point by one rotation command generated by the manual operation device 40.