Paul Jenkins, 52, was reported missing from an address in Chorley after last being in contact with his family on Tuesday, July 30.
Lancashire Police are now "increasingly concerned for the welfare" of Paul.
He has connections with the Withnell and Leyland areas and also has family in Wales.
He is described as a white male, 5ft 6ins tall, with a dark complexion, black balding hair, dark eyes and has a musical tattoo on the top of one of his arms.
A Lancashire Police spokesman said: "The photo of Paul is an old picture and may not portray a current likeness of him.
"If anybody has any information about Mr Jenkins, please ring 101 and give log number LC-20190902-0972."