An ink jet recording device includes a recording head, a conveying member, a platen, a supporting member, and a driving member. The recording head ejects ink droplets onto a recording medium. The conveying member conveys the recording medium in a conveying direction. The recording medium has a leading edge and a trailing edge in the conveying direction. The platen is disposed in confrontation with the recording head to support the recording medium while keeping a predetermined distance from the recording head. The supporting member is disposed in the platen to slide in the conveying direction while supporting the recording medium. The driving member drives the supporting member to start sliding in the conveying direction at a starting timing corresponding to a position of at least one of the leading edge and the trailing edge.