A　method　to　determine　the　3D　position　of　endoscope　using　magnetic　fields　is　proposed　as　solution　for　the　problem　of　positioning　the　endoscope　inside　the　patient＇s　body.　Key　component　to　the　approach　is　the　use　of　a　3D　magnetic　sensor　attached　to　the　endoscope.　A　practical　system　is　developed,　which　includes　a　controlling　part,　a　receiving　part,　a　power　amplifier,　emitting　coils,　receiving　tip　and　printed　circuit　and　analog-to-digital　board.　The　theoretical　principle　of　the　approach　is　discussed.