A measured data pass-fail discriminating apparatus comprising a digital display type measuring instrument (1) and a data discriminating device (2) for discriminating pass or fail of measured data inputted from the measuring instrument (2). In the data discriminating device (2), the upper limit value (HH) and the lower limit value (LL) are set, and the upper limit preview value (H) and the lower limit preview value (L) are set closer to reference values than the upper limit value (HH) and lower limit value (LL). An alarm signal is given when the measured data having the same number as the preset judging frequency (Jl) continuously lies in ranges between the upper limit preview value (H) and the upper limit value (HH) and between the lower preview value (L) and the lower limit value (LL), or when the measured data exceed the upper limit value (H) and the lower limit value (L).