This invention provides a paper-blocking mechanism and paper processing device using the same. The paper-blocking mechanism comprises a paper holder, a shaft connecting to a power source and driving a paper feeding portion, a restriction portion disposed on the shaft and moving between a first position and second position when the shaft is rotating, a paper blocking portion comprising a paper blocking plate and coupled to the paper processing device, wherein the restriction portion abuts the paper blocking plate to cause the paper holder in a paper blocking position when the restriction portion is in the first position, and the restriction portion doesn't abut the paper blocking plate to cause the paper holder in a paper feeding position when the restriction portion is in the second position.