A phase detector (5; 5A; 5B), comprising: a signal selector (4; 4A; 4B) configured to select, as a selected sensor signal, one of a plurality of sensor signals (U1; V1; W1) each having a signal level corresponding to a phase of a rotor; a bias level generator (2; 2A; 2B) configured to divide a signal level difference between a pair of sensor signals at a first ratio, the pair of sensor signals including the selected sensor signal and other sensor signal of the plurality of sensor signals (U1; V1; W1) other than the selected sensor signal, to generate a first bias level (Luv; Lwu; Lvw); wherein the bias level generator (2; 2A; 2B) is configured to divide a first signal level difference between the selected sensor signal and a first sensor signal having a signal level greater than that of the selected sensor signal at the first ratio to generate the first bias level (Luv; Lwu; Lvw), and wherein the bias level generator (2; 2A; 2B) is configured to divide a second signal level difference between the selected sensor signal and a second sensor signal having a signal level smaller than that of the selected sensor signal at the first ratio to generate a second bias level (Luv; Lwu; Lvw); and a phase information detector configured to generate a threshold level (Lv(n)) corresponding to the phase of the rotor, and to detect the signal level of the selected sensor signal reaching the threshold level (Lv(n)); wherein the phase information detector is configured to divide a signal level section (Lint) at a second ratio corresponding to the phase of the rotor, the signal level section (Lint) having an upper end (L UP) and a lower end (L LO) respectively corresponding to the first bias level (Luv; Lwu; Lvw) and the second bias level (Luv; Lwu; Lvw), to generate the threshold level (Lv(n)). a signal selector (4; 4A; 4B) configured to select, as a selected sensor signal, one of a plurality of sensor signals (U1; V1; W1) each having a signal level corresponding to a phase of a rotor; a bias level generator (2; 2A; 2B) configured to divide a signal level difference between a pair of sensor signals at a first ratio, the pair of sensor signals including the selected sensor signal and other sensor signal of the plurality of sensor signals (U1; V1; W1) other than the selected sensor signal, to generate a first bias level (Luv; Lwu; Lvw); wherein the bias level generator (2; 2A; 2B) is configured to divide a first signal level difference between the selected sensor signal and a first sensor signal having a signal level greater than that of the selected sensor signal at the first ratio to generate the first bias level (Luv; Lwu; Lvw), and wherein the bias level generator (2; 2A; 2B) is configured to divide a second signal level difference between the selected sensor signal and a second sensor signal having a signal level smaller than that of the selected sensor signal at the first ratio to generate a second bias level (Luv; Lwu; Lvw); and wherein the bias level generator (2; 2A; 2B) is configured to divide a first signal level difference between the selected sensor signal and a first sensor signal having a signal level greater than that of the selected sensor signal at the first ratio to generate the first bias level (Luv; Lwu; Lvw), and wherein the bias level generator (2; 2A; 2B) is configured to divide a second signal level difference between the selected sensor signal and a second sensor signal having a signal level smaller than that of the selected sensor signal at the first ratio to generate a second bias level (Luv; Lwu; Lvw); and a phase information detector configured to generate a threshold level (Lv(n)) corresponding to the phase of the rotor, and to detect the signal level of the selected sensor signal reaching the threshold level (Lv(n)); wherein the phase information detector is configured to divide a signal level section (Lint) at a second ratio corresponding to the phase of the rotor, the signal level section (Lint) having an upper end (L UP) and a lower end (L LO) respectively corresponding to the first bias level (Luv; Lwu; Lvw) and the second bias level (Luv; Lwu; Lvw), to generate the threshold level (Lv(n)).