A process contains in which heating and fixing an image of a toner on a recording medium is performed by heating one or more heat-transfer media by a heating element, and pressing the recording medium bearing the toner image to one of the heat-transfer media. At least one of the heat-transfer media is a belt heat-transfer medium with or without the application of an oil whose amount is 4 mg or less per A4 size, and the toner contain a binder resin and a releasing agent, has a weight-average particle diameter Dv of 3.0 to 7.0 .mu.m, a particle diameter distribution Dv/Dn of 1.00 or more and 1.25 or less, wherein Dn is a number-average particle diameter, and an average shape factor SF-1 of 100 to 150 and contains toner particles having a shape factor SF-1 of 160 or more in an amount of 10% by number or less.