To provide a self-traveling soil improving machine capable of securing a storage quantity from the aspect of working efficiency, and capable of restraining reduction in productivity by shortening interruption time of work by preventing the problem such as a bridge and blocking-up while minimizing the whole height from the aspect of transport performance.

This self-traveling soil improving machine has a soil improving material supply device 7 supplying a soil improving material by a fixed quantity to sediment to be reformed, and a soil improving material storage device 8 having a storage tank 28 storing the soil improving material supplied to this soil improving material supply device 7, and is characterized in that the soil improving material storage device 8 has a column 20 selectively held and fixed in an upper position and a lower position to a body of the self-traveling soil improving machine, and the storage tank 28 having the lower end connected to the soil improving material supply device 7 and having the upper end formed of an expandable construction material connected to the column.