A method for producing a forged crankshaft including journals (J1-J4) serving as a center of rotation, pins (P1-P3) decentered from the journals (J1-J4) and located at a first position, a second position and a third position, respectively, having phase differences of 120 degrees thereamong, crank arms (A1-A8) connecting the journals (J1-J4) and the pins (P1-P3), and counterweights (W1-W4) integrated with some or all of the crank arms (A1-A8), the method comprising: a first preforming step of pressing a workpiece by a first pair of dies, wherein the first pair of dies includes pin processing portions (31b, 32b) to come into contact with the portions to be formed into the pins (P1-P3) and journal processing portions (31a, 32a) to come into contact with the portions to be formed into the journals (J1-J4); a second preforming step of pressing the afore obtained initial blank by a second pair of dies with a pressing direction, to decenter the portions to be formed into the pins located at the first and third positions (P1, P3) towards respective opposite sides; a final preforming step of pressing the afore obtained intermediate blank by a third pair of dies to further decenter the portions to be formed into the pins located at the first and third positions (P1, P3); characterised in that: the workpiece is a billet or a stepped blank; the stepped blank has small sectional areas in the portions to be formed into the pins (P1-P3) and in the portions to be formed into the journals (J1-J4), the small sectional areas being smaller than a total of a sectional area of a portion to be formed into a crank arm (A1-A8) incorporating a counterweight (W1-W4) and a sectional area of a portion to be formed into the counterweight (W1-W4) integrated with the crank arm (A1-A8); and in the first preforming step, the workpiece is pressed by the pin processing portions (31b, 32b) and the journal processing portions (31a, 32a) to decrease sectional areas of portions of the workpiece to be formed into the pins (P1-P3) and sectional areas of portions of the workpiece to be formed into the journals (J1-J4), thereby forming said portions into flat portions, and to decenter the flat portion to be formed into the pin located at the second position; in the second preforming step, the pressing direction is perpendicular to the afore decentering direction of the flat portion to be formed into the pin located at the second position. a first preforming step of pressing a workpiece by a first pair of dies, wherein the first pair of dies includes pin processing portions (31b, 32b) to come into contact with the portions to be formed into the pins (P1-P3) and journal processing portions (31a, 32a) to come into contact with the portions to be formed into the journals (J1-J4); a second preforming step of pressing the afore obtained initial blank by a second pair of dies with a pressing direction, to decenter the portions to be formed into the pins located at the first and third positions (P1, P3) towards respective opposite sides; a final preforming step of pressing the afore obtained intermediate blank by a third pair of dies to further decenter the portions to be formed into the pins located at the first and third positions (P1, P3); characterised in that: the workpiece is a billet or a stepped blank; the stepped blank has small sectional areas in the portions to be formed into the pins (P1-P3) and in the portions to be formed into the journals (J1-J4), the small sectional areas being smaller than a total of a sectional area of a portion to be formed into a crank arm (A1-A8) incorporating a counterweight (W1-W4) and a sectional area of a portion to be formed into the counterweight (W1-W4) integrated with the crank arm (A1-A8); and in the first preforming step, the workpiece is pressed by the pin processing portions (31b, 32b) and the journal processing portions (31a, 32a) to decrease sectional areas of portions of the workpiece to be formed into the pins (P1-P3) and sectional areas of portions of the workpiece to be formed into the journals (J1-J4), thereby forming said portions into flat portions, and to decenter the flat portion to be formed into the pin located at the second position; in the second preforming step, the pressing direction is perpendicular to the afore decentering direction of the flat portion to be formed into the pin located at the second position. the workpiece is a billet or a stepped blank; the stepped blank has small sectional areas in the portions to be formed into the pins (P1-P3) and in the portions to be formed into the journals (J1-J4), the small sectional areas being smaller than a total of a sectional area of a portion to be formed into a crank arm (A1-A8) incorporating a counterweight (W1-W4) and a sectional area of a portion to be formed into the counterweight (W1-W4) integrated with the crank arm (A1-A8); and in the first preforming step, the workpiece is pressed by the pin processing portions (31b, 32b) and the journal processing portions (31a, 32a) to decrease sectional areas of portions of the workpiece to be formed into the pins (P1-P3) and sectional areas of portions of the workpiece to be formed into the journals (J1-J4), thereby forming said portions into flat portions, and to decenter the flat portion to be formed into the pin located at the second position; in the second preforming step, the pressing direction is perpendicular to the afore decentering direction of the flat portion to be formed into the pin located at the second position.