Abstract: A continuous powder catalyst supply apparatus and a catalyst supply system that is suitable for olefin gas phase polymerization. The supply apparatus comprises a catalyst storage chamber having a catalyst inlet port and a catalyst supply port for transmitting the catalyst to the reactor. Inside the catalyst storage chamber is a catalyst supply mechanism which substantially continuously supplies the catalyst to the catalyst supply port, and a forcible discharge mechanism which forcibly discharges the catalyst, supplied from the catalyst supply mechanism, through the catalyst supply port with a pressurized gas. The apparatus can be used to supply the catalyst to the reactor with low amounts of pressurized gas. Further, the system can be configured so as to avoid contamination of stored catalyst by reactant gas.