An image forming method, comprising discharging an actinic radiation-curable inkjet ink by using a line head (110 - 113) to thereby land the inkjet ink on a recording medium, and conveying the recording medium, wherein the line head (110 - 113) comprises a long-size recording element train (170 - 173); the long-size recording element train comprises a plurality of modules (160 - 163); each module (160 - 163) of the plurality of modules comprises at least one short-size recording element train (150 - 153) having a plurality of recording elements arrayed in a direction orthogonal to a conveying direction of the recording medium; the plurality of modules (160 - 163) are disposed in zigzags in a state of having a superposed region where end parts of at least two modules, out of the plurality of modules, adjacent to each other in a direction of the short-size recording element train (150 - 153), are superposed in the direction orthogonal to the conveying direction of the recording medium; a time interval is 25 ms or longer, the time interval being, from a landing time when a first ink is discharged from the short-size recording element train (150 - 153) in one module of at least two modules in the superposed region and landed on the recording medium, to a landing time when the first ink or a second ink of the same color-based ink as the first ink is discharged from the short-size recording element train (150 - 153) in the other module (160 - 163) and landed on the recording medium; the actinic radiation-curable inkjet ink comprises at least a radical polymerizable compound, a gelling agent and a colorant and undergoes temperature-induced reversible sol-gel phase transition; and the gelling agent is at least one compound among compounds represented by formulae (G1) and (G2): Formula (G1): R1-CO-R2 Formula (G2): R3-COO-R4 wherein R1 to R4 each independently denote a hydrocarbon group having a straight chain moiety having 12 or more carbon atoms; and the actinic radiation-curable inkjet ink has a content of the gelling agent in which R1 to R4 have 20 or more carbon atoms of 0 to 0.9mass% relative to a total mass of the actinic radiation-curable inkjet ink; and a content of the gelling agent in which R1 to R4 have 12 or more carbon atoms of 1.0 to 2.4mass% relative to a total mass of the actinic radiation-curable inkjet ink; and the ink has a complex viscosity of 50 to 300 Pa·s at a temperature of the ink when the actinic radiation-curable inkjet ink is landed on the recording medium. wherein R1 to R4 each independently denote a hydrocarbon group having a straight chain moiety having 12 or more carbon atoms; and the actinic radiation-curable inkjet ink has a content of the gelling agent in which R1 to R4 have 20 or more carbon atoms of 0 to 0.9mass% relative to a total mass of the actinic radiation-curable inkjet ink; and a content of the gelling agent in which R1 to R4 have 12 or more carbon atoms of 1.0 to 2.4mass% relative to a total mass of the actinic radiation-curable inkjet ink; and the ink has a complex viscosity of 50 to 300 Pa·s at a temperature of the ink when the actinic radiation-curable inkjet ink is landed on the recording medium. <EOS>