The 31 year old striker who scored 8 goals for the Millers last season has been tormented with illness over the last couple of seasons and as one of the high wage earners will have been offered a much lesser deal this time around.
Speaking to the Millers official website, Boss Alan Knill said: "In some ways I am not surprised about his decision as it comes down to money at the end of the day. Martin also comes from around that area and I understand he is planning to have a house built in the area."
Butler was a join record transfer fee for the Millers at the magical £150k mark, his record for the club was Played 96 +8sub, Scored 29 goals and was sent off once, at Blackpool last season.
THIS MOVE HAS NOW BEEN CONFIRMED.