A brushless motor position detection device has a set of first Hall elements (main Hall ICs 18 for detecting magnetic pole positions) and a set of second Hall elements (sub-Hall ICs 19 for detecting magnetic pole positions) mounted on a plane facing a magnetic pole position detecting magnet 16 for detecting the position of a rotor 12. They are subjected to offset adjustment and are mounted in such a manner that the difference between the maximum value of the magnetic flux density at the mounting positions of the first Hall elements and the maximum value of the magnetic flux density at the mounting positions of the second Hall elements is held within a prescribed limit (mounted in such a manner as to have the offset of a prescribed machine angle in the circumferential direction) to bring the detection accuracy of the plurality of sets of the Hall elements into agreement.