He and his wife, Jill Biden, wearing black masks, laid a wreath in a visit that was not publicly announced before the trip. Mr. Biden, a practicing Catholic, made the sign of the cross.
“Thanks for your service,” Mr. Biden said, appearing to salute another individual from afar, as he walked out.
Mr. Biden, the presumptive Democratic nominee, cut a sharp visual contrast with President Trump, who has generally declined to wear a mask in public despite federal health guidance, including at a memorial service on Monday.
The Bidens’ late son, Beau Biden, served in the Iraq war. He died of brain cancer five years ago this week.
The visit comes as some Democrats, including some close allies, have grown impatient to see Mr. Biden leave his Wilmington, Del., home and find ways to connect publicly, even in the era of social distancing. Mr. Biden’s campaign did not immediately have a comment when asked whether his Memorial Day outing signaled the beginning of more public appearances.
Mr. Biden, 77, and his campaign advisers have said that they intend to abide by the public safety recommendations that have, so far, made rallies and other campaign events impossible, though some states are increasingly lifting restrictions.
The visit comes as the Bidens also released a video to commemorate Memorial Day, a sign of the virtual campaign still underway, in stark contrast to the parades and in-person commemorations often held throughout the country to mark the day.