An apparatus for removing rust from a square pipe is provided to supply a square pipe safely and exactly by pushing the square pipe to a coating device at a rate identical to an initial influx rate. A square pipe is pushed to first and second brush units(300,400) through a first feeding roller(200) and guiding rollers(110-112). The square pipe is pushed to a coating device(20) through a second feeding roller(500) and guiding rollers(113-115). The square pipe passing through first and second brush units is input and output at the same rate. The first and second feeding rollers receive power through belts(132) coupling the guiding rollers without an additional driving motor.
