The 2004 Australian Under-21 Individual Speedway Championship was the 18th running of the Australian Under-21 Individual Speedway Championship organised by Motorcycling Australia. The final took place on 31 January 2004 at the Undera Park Speedway in Undera, Victoria. The championship was won by defending champion, Adelaide's Rory Schlein. Robert Ksiezak from Adelaide was second with another South Australian, Matt Wethers, in third place.