Save-A-Lot opened Thursday.
Chain spokeswoman Chon Tomlin tells The Press of Atlantic City armed guards normally staff Save-A-Lot's 1,400 other stores, particularly in urban areas, because the retailer can't raise prices because of a lot of theft.
The guards are off-duty or retired law enforcement officers.
Customer Mara Swain tells the newspaper she likes their presence because "Atlantic City's not the safest place."
The last supermarket in Atlantic City, IGA, shut its doors in 2006 after two years in business.
Information from: The Press of Atlantic City