To provide a printing system capable of improving convenience.

A mail server 12 receives e-mail including data being a printing object, determines whether security printing is executed or collective printing is executed by a prescribed condition, and transmits a determining result to a reservation control server 13 together with e-mail. The reservation control server 13 attaches the same reservation identifier to printing data belonging to a printing object data group being an object of the collective printing, and attaches a reservation identifier different from this identifier to data being no object of the collective printing. A user indicates printing of the printing data by the reservation identifier, and the reservation control server 13 requests input of a password when the indicated printing data is for executing the security printing, and starts printing processing when the inputted password coincides with an issued password.