This invention is about a commercial anti-theft device, more specifically involving in a narrow acousto-magnetic (AM) anti-theft marker having multiple resonators. A type of narrow AM anti-theft marker with multiple resonators includes an elongated housing, resonators, housing cover and magnetic bias pieces. The resonators are placed inside the cavity of the housing. The aforementioned housing bottom is connected to the housing cover so that the resonators are enclosed inside the housing. The number of aforementioned resonators is two to five; the width of resonators is 1.6-5.3 mm. This anti-theft marker has high performance/cost ratio. Because resonators with smaller than conventional width are used, it meets the customer demands for protecting smaller or more exquisite merchandise. Meanwhile it saves expensive amorphous alloys of resonators and alloys of bias and double tapes, led to lower raw material costs.