PURPOSE: To provide a method for easily sensing the change or variation of the consistency of woven fabric and an apparatus for executing the method.

CONSTITUTION: The apparatus for sensing the variation of the consisting of woven fabric comprises a light reflection sensor 1, an operational amplifier buffer 3 having an electric input unit connected to the output unit of the sensor 1, means 2 for averaging and informing the signal picked up by the output unit of the sensor 1, means 4 for differentially amplifying the signals of the output units of the buffer and means, and means 5 for comparing the signal output from the means 4 with the known signal decided previously.