Lee Simpson, 43, was last seen leaving his home in Barlow near Selby at around 2.45pm on Monday and may currently be in York.
Officers have been carrying out searches and are becoming increasingly concerned for his welfare.
Mr Simpson is of medium build and was last seen wearing a grey fluffy cardigan jacket, grey jogging trousers and black trainers.
Anyone who thinks they may have seen him, or has any other information that could help, is urged to contact North Yorkshire Police immediately on 101.
Please quote reference NYP22982023-0520.