A support driver for a seat and a support assembly including the same that is using a tube and a structure of a mat that is moved by an inflation and a deflation of the tube. According to an embodiment of the present disclosure, the support driver coupled to a seat frame includes: a support portion coupled to the seat frame; a tube coupled to the support portion; and a mat coupled to the support portion so as to allow the mat to be movable in a direction that is away from the support portion or in a direction that is adjacent to the support portion, with the tube being provided therebetween, in which the tube is configured to push the mat by being inflated according to an operation of a pump that is connected to the tube by a hose.