The body of the 25-year-old man, who was not identified, was found hanging from a tree in a forest not far from his house in Moo 4 village in Tambon Thasak in Muang district at 9am.
A doctor who inspected the scene said he believed the man had died about 10 to 12 hours earlier.
His relatives told police that the man had become depressed after his wife had left him and remarried about two months ago, taking their daughter with her.
The man's relatives said he had tried to meet his daughter on Wednesday but his request was turned down by the ex-wife and her relatives.
The man was seen leaving his house in the evening before his body was found.