Acereal flow regulator devicefor roller mills, comprises a feed roller (3) disposed downstream of the feed hopper (4), and a mobile baffle (6) which can be spaced apart from said feed roller (3) in order to regulate the flow of cereal towards the grinding rolls (1,1'). The device comprises a deviator element (11) of length substantially equal to the length of said baffle (6), and which is disposed downstream of this latterand is mounted on a hinged support (12, 13) which varies its position in relation to the throughput of the cereal in order to always direct it between the grinding rolls (1,1').