A pole base loading apparatus and a main chassis for a magnetic recording/reading device having an improved structure. The pole base loading apparatus includes a pair of pole base units for guiding a tape so that the tape is wound around a head drum as it reciprocates on a main chassis, a pair of loading gears respectively linked to the pole base units and gear-engaged with each other, and a loading unit for rotating the loading gears. At least one of the pair of loading gears has a hook installed therein so that the loading gear is coupled to the main chassis.