In a digital ramp phase type gyro in which a ramp signal RAM is produced by repeatedly accumulating step values sequentially generated corresponding to an input angular rate until the accumulated value exceeds a threshold value THR or -THR and the ramp signal RAM is used to modulate the phases of clockwise and counterclockwise light beams to cancel the phase difference therebetween, a comparing part 38 compares the threshold values THR and -THR and the ramp signal RAM and, when the ramp signal RAM exceeds either one of the threshold values THR and -THR, outputs the threshold value THR or -THR and a subtractor 41 subtracts the output threshold value from the accumulated value at that time, thereby causing a flyback of the ramp signal RAM. The output from a synchronous detector 23 at this time is latched as an error signal in a latch circuit 31 and the error signal is integrated by an integrating filter 32 to generate a correcting signal. The correcting signal is added to a reference value Er in a circuit 37 to produce corrected threshold values THR and -THR and the phase difference between the clockwise and counterclockwise light beams immediately prior to the flyback is always held to be 2n.pi. rad.