To provide a circuit for measuring the residual quantity of a continuous strip body in which accuracy of measurement can be enhanced.

Pulse with of a transmitted light and a shielded light outputted from a slit sensor 16 is counted by 8 bit binary counters 32a and 32b using a reference clock generated from a counter reference clock generator 31 and counts T1, T2, ... and S1, S2, ... are latched for a specified period by 8 bit data latch circuits 35a and 35b. Upon receiving a read request signal from the system by 8 bit data bus gate circuits 36a and 36b, any one of the latched counts T1, T2, ... and S1, S2, ... is delivered.