Abstract: A knockdown chair for children easily assembled and disassembled, and maintaining a desired connection strength for a long time. The knockdown chair comprises a square seat plate having an insert projection on its side surface, a plurality of support beams engaging with and surrounding the seat plate by reception of individual insert projections of the seat plate and each having a reception slit at its side surface and a pair of reception holes on its opposed ends, a plurality of connection members connecting the support beams to each other at corners of the seat plate and each having three inserts in order to be coupled not only to corresponding neighbor support beams but also to a leg member, and the leg member coupled to the connection member for supporting the seat plate and the support beams. The reception slit and the reception holes of the parts of the chair are preferably provided with elastic soft layers made of a soft synthetic resin material for facilitating assembly and disassembly of the chair.