A magnetic field generator (10) which generates a high uniformity magnetic field at a plurality of locations is provided. The magnetic field generator (10) includes a pair of plate yokes (12a),(12b) which are faced to each other with a gap (G) in between. A pair of mutually opposed magnetic poles (14a),(14b), and another pair of mutually opposed magnetic poles (16a),(16b) are provided between the plate yokes (12a),(12b). The magnetic poles (14a),(14b) respectively include permanent magnet groups (18a),(18b) which are disposed on mutually opposed surfaces of the plate yokes (12a),(12b). Pole pieces (20a),(20b) are fixed to mutually opposed surfaces respectively of the permanent magnet groups (18a),(18b). The magnetic poles (16a),(16b) respectively include permanent magnet groups (22a),(22b) which are disposed on mutually opposed surfaces of the plate yokes (12a),(12b). Pole pieces (24a),(24b) are fixed to mutually opposed surfaces respectively of the permanent magnet groups (22a),(22b). Magnetic field uniformity spaces (F1),(F2) are formed between the pole pieces (20a),(20b) and between the pole pieces (24a),(24b) respectively.