To provide a mobile type silo and a plant system to flexibly comply with the change of kinds of powder even when various kinds of ready-mixed concrete are manufactured and be realized at a low cost through comparatively simple constitution.

A plant system comprises a tank 3 to store a given amount of powder; a metering apparatus 7 to meter powder flowing out from the under side of the tank 3; a root blower 8 to effect pneumatic transport of powder after metering; and a rotary feeder 9. A mobile type silo 2 the whole of which is movable is coupled to a plant, comprising a bin 21 to store a given amount of powder; a metering apparatus 23 to meter powder flowing out from the under side of the bin 21; and a mixer 25 to mix together powder, aggregates, and water, through a transport pipe 11. Powder pneumatically transported by the root blower 8 and the rotary feeder 9 flows in the mixer 25 through the transport pipe 11.