There is provided a magnetic field generator 10 which is capable of
generating a uniform magnetic field of a desired intensity easily and
stably without increasing running cost. The magnetic field generator 10
includes a pair of plate yokes 12a, 12b. The plate yokes 12a, 12b have
opposed surfaces provided with magnetic pole 14a, 14b respectively. The
magnetic pole 14a includes a permanent magnet group 16a whereas the
magnetic pole 14b includes a permanent magnet group 16b. Each of the
permanent magnet groups 16a, 16b is formed substantially in a disc like
shape, as an integral body made of a plurality of permanent magnets 20
and a plurality of heat conducting members 22. Tubular heaters 34, buried
in the plate yokes 12a, 12b, generate heat, which is conducted via the
plate yokes 12a, 12b to each permanent magnet 20 and each heat conducting
member 22 which constitute the permanent magnet groups 16a, 16b.