A level with magnetic device relates to a measuring instrument. That level includes a case body and a bubble cell on the case body, and it is characterized in that the cross section of the bottom of the case body, being the location of the reference plane, has a profiled shape, and furthermore by this is constituted a profiled slot on the bottom of the case body, a magnet is placed inside the profiled slot on the bottom of said case body, an elastic retaining bracket is pressed on top of the magnet, and the shapes of that elastic retaining bracket and the profiled slot are complementarily matched. That level solves the problem of instability of precision of the contemporary level with magnetic device, and it is widely applicable in the level industry.