PURPOSE: To permit high efficient weighing with no fear by detecting when the stable state has been reached after energization of a power supply, thereby to generates an alarm, and by starting the weighing after the alarm has been generated.

CONSTITUTION: As a power supply is turned ON, power is fed from a power supply circut 1 to a timer 2 and the timer 2 clocks a time period that has passed after energization of the power supply. This clock output is supplied to a comparator 4. Whereas, a time setting value is supplied to the comparator 4 from a time setting circuit 3. The time setting value is preset on the basis of the previous knowledge how long time it takes for a balance to reach the stable state after energization of the power supply. Therefore, when the clock output from the timer 2 becomes equal to the time setting value, the comparator 4 issues coincidence output and sends it to a signal generating circuit 5, so that a stability signal is generated from the signal generating circuit 5 to illuminate a lamp 6. Thus, it becomes possible to start the desired weighing after noticing that the balance has reached the stable state.