Provided are an inkjet printer for both surface printing and back printing which is capable of performing both of surface printing and back printing while continuously conveying a web-shaped print base material (12) at high speed, and an inkjet printing method using the inkjet printer. The inkjet printer includes: a first white inkjet head (20a) configured to discharge a white aqueous ink to a surface of the web-shaped print base material (12) in a case of surface printing; a first drum-type drying unit (22a) configured to dry the white aqueous ink in the case of surface printing; a second white inkjet head (20b) configured to discharge a white aqueous ink to a surface of the web-shaped print base material (12) in a case of back printing; and a second drum-type drying unit (22b) configured to dry the white aqueous ink in the case of back printing.