To prevent an ejecting port from being blocked by an aggregated or precipitated substance.

A pre-coating head for ejecting a pre-coating liquid drop for aggregating or precipitating ink pigment component, and four ink jet heads for ejecting ink drops are arranged in order along the direction of paper conveyance. Immediately after a paper jam detecting section detects the jam of paper between an ejecting surface and a conveyance belt for conveying paper (S102), a purge control section forcibly discharges ink from the ejecting port of the ink jet head opposing to the paper (S105). When the head elevation and lowering control section moves the ink jet head 1 to a maintenance position (S107), the purge control section stops forcible discharge of ink (S108).