Benjamin Doherty, 26, has been missing from his home in Highmoor Road, Caversham, since Wednesday morning.
He is white, slim, around 5ft 8ins, with dark brown hair and a beard.
Sergeant Paul Jacobs said: "It is out of character for Benjamin to go out during the day and not return.
"We are not aware of any dispute of any reason for him to stay away from home. We believe that he has connections to the Manchester area."
Call 101 or Crimestoppers anonymously on 0800 555 111.