It happened Sunday morning at 5:30 a.m., at the Applebee's in the Suburban Plaza Shopping Center.
Police say the restaurant was closed when the man broke in and stole a safe containing an undisclosed amount of cash.
The burglary was caught by surveillance cameras.
The suspect is described as a white man, about 6 feet tall with brown hair. He was wearing a gray short-sleeved shirt, blue jeans, dark shoes and black gloves. Police believe he fled the scene in a dark-colored two-door vehicle.
Anyone with information is asked to contact Detective Greg D'Elia at (302) 366-7110 x 132 or greg.delia@cj.state.de.us
You can send an anonymous text message tip by texting 302NPD and your message to TIP411.
Information can also be provided anonymously to Crime Stoppers at 1-800-TIP-3333 or via the internet at www.tipsubmit.com where a reward may be available.