Samuel Mitson, 34, was last seen in Stanley Road at 4.15pm on Friday 4 March 2022 and was said to be very upset.
He is described as white, five feet eight inches tall, of slim build and with short brown hair with stubble. He was wearing a brown jumper, blue jeans, a black thin Puffa-style jacket and trainers.
Chief Inspector Andy Bell, of Dorset Police, said: “Samuel has been very upset recently and we need to find him urgently to ensure he is safe and well.
“I would ask anyone who has seen Samuel or a man matching the description given to please contact Dorset Police.
“I am also making a direct plea to Samuel if you see this appeal to please make contact with us or your family and let us know where you are, as we just want to ensure you are safe.”
Anyone with information or knowledge as to Samuel’s whereabouts is asked to contact Dorset Police at www.dorset.police.uk, via email 101@dorset.pnn.police.uk or by calling 101, quoting incident number 4:550.