An inkjet printer (10A, 10B) for aqueous ink which is configured to perform image formation by discharging aqueous ink to a web-shaped printing base material, comprising: a conveyance mechanism (14, 14a, 14b) configured to continuously convey the web-shaped printing base material; a respective single-pass system inkjet head (16a, 16b, 16c, 16d, 16e) configured to discharge the aqueous ink of respective color, by a single-pass system, the aqueous ink to a surface of the web-shaped printing base material conveyed by the conveyance mechanism (14, 14a, 14b); and a respective surface pre-heating unit (18a, 18b, 18c, 18d, 18e) which is arranged on an upstream side of conveyance from the respective single-pass system inkjet head (16a, 16b, 16c, 16d, 16e) 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, wherein heating by the surface pre-heating unit (18a, 18b, 18c, 18d, 18e) is performed through use of hot air blowing means (42,52) for applying hot air to the surface of the web-shaped printing base material, and characterized in that the hot air blowing means (42,52) comprises: a nozzle group main body having a plurality of slit-shaped hot air blowing nozzles arranged so as to form gaps therebetween, the plurality of slit-shaped hot air blowing nozzles each having a slit-shaped hot air outlet port extending in a width direction of the web-shaped printing base material; and a suction mechanism configured to suck an atmosphere of the gaps formed in the nozzle group main body. a conveyance mechanism (14, 14a, 14b) configured to continuously convey the web-shaped printing base material; a respective single-pass system inkjet head (16a, 16b, 16c, 16d, 16e) configured to discharge the aqueous ink of respective color, by a single-pass system, the aqueous ink to a surface of the web-shaped printing base material conveyed by the conveyance mechanism (14, 14a, 14b); and a respective surface pre-heating unit (18a, 18b, 18c, 18d, 18e) which is arranged on an upstream side of conveyance from the respective single-pass system inkjet head (16a, 16b, 16c, 16d, 16e) 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, wherein heating by the surface pre-heating unit (18a, 18b, 18c, 18d, 18e) is performed through use of hot air blowing means (42,52) for applying hot air to the surface of the web-shaped printing base material, and characterized in that the hot air blowing means (42,52) comprises: a nozzle group main body having a plurality of slit-shaped hot air blowing nozzles arranged so as to form gaps therebetween, the plurality of slit-shaped hot air blowing nozzles each having a slit-shaped hot air outlet port extending in a width direction of the web-shaped printing base material; and a suction mechanism configured to suck an atmosphere of the gaps formed in the nozzle group main body.