An image forming method includes the steps of:(1) forming a first unfixed image of color toner on one side of a transfer material, wherein the color toner has a weight average particle size of 3 to 7 .mu.m and includes color toner particles having a particle size of 4 .mu.m or less in a range of 10 to 70 by number, color toner particles having a particle size of 5.04 .mu.m or less in a range of 40% by number or more, color toner particles having a particle size of 8 .mu.m or more in a range of 2 to 20% by volume, and color toner particles having a particle size of 10.08 .mu.m or more in a range of 6% by volume or less; (2) heating and melting the color toner of the first unfixed image by heating, pressing and fixing means which includes a rotation body for fixing having an elastic layer to fix the first unfixed image to the one side of the transfer material; (3) forming a second unfixed image of color toner on the other side of the transfer material, wherein the color toner has a weight average particle size of 3 to 7 .mu.m and includes color toner particles having a particle size of 4 .mu.m or less in a range of 10 to 70% by number, color toner particles having a particle size of 5.04 .mu.m or less in a range of 40% by number or more, color toner particles having a particle size of 8 .mu.m or more in a range of 2 to 20% by volume, and color toner particles having a particle size of 10.08 .mu.m or more in a range of 6% by volume or less; and (4) heating and melting a color toner of the second fixed image by the heating, pressing and fixing means to fix the second unfixed image to the other side of the transfer material, whereby color images are formed on both sides of the transfer material.