According to one embodiment, a magnetic recording and reproducing device includes a magnetic recording medium, a recording unit, and a reproducing unit. The magnetic recording medium includes a first track including first and second sub-tracks extending in a first direction. The second sub-track is arranged with the first sub-track in a second direction intersecting the first direction. The recording unit records information in the first and second sub-tracks. The reproducing unit reproduces the information recorded in the first and second sub-tracks while opposing the first, second sub-tracks, and a boundary between the first and second sub-tracks. The first sub-track includes first magnetic recording components including first and second components. The second sub-track includes second magnetic recording components including third and fourth components. A first recording symbol is formed of the first and third components. A second recording symbol is formed of the second and fourth components.