Provided is an inkjet printer which is capable of preventing ink flow and color blurring as well as color mixing during multicolor printing when image formation is performed with aqueous ink on a web-shaped printing base material, and an inkjet printing method using the inkjet printer. The inkjet printer is configured to perform image formation by discharging aqueous ink to a web-shaped printing base material, and comprises: a conveyance mechanism configured to continuously convey the web-shaped printing base material; a single-pass system inkjet head configured to discharge, by a single-pass system, the aqueous ink to a surface of the web-shaped printing base material conveyed by the conveyance mechanism; and a surface pre-heating unit which is arranged on an upstream side of conveyance from the single-pass system inkjet head and is configured to heat at least the surface of the web-shaped printing base material, wherein image formation through use of the single-pass system inkjet head is performed on the web-shaped printing base material heated by the surface pre-heating unit.