Abstract: A biological signal detecting apparatus includes a BPF to which a biological signal is input via a lead directly connected to a subcutaneous tissue that emits the biological signal including a predetermined signal of a first frequency and which outputs a filtered biological signal by filtering a biological event signal of a predetermined frequency including the first frequency; and a peak detecting means to which at least the filtered biological signal is input and which detects a peak location of the biological event signal. The BPF includes a first order HPF which filters a frequency higher than a second frequency and a first order LPF which filters a frequency lower than a third frequency. The HPF and the LPF are connected in series between the lead and the peak detecting means. A difference between the second frequency and the third frequency is less than or equal to 10 Hz.