To provide an image forming device capable of preventing disturbance of the toner image carried on a sheet, and the generation of wrinkles on the sheet.

This image forming device is provided with a fixing device for letting the toner image fixed on the sheet 5 by insert-transporting the sheet 5 between a fixing roller 1 and the pressure roller 2 (rollers pair) being vertically arranged, and an inlet guide 3 for guiding the sheet 5 to a nip 9 between the fixing roller 1 and the pressure roller 2 in the fixing device. In this case, by equipping switch structures (arm 11, link 12, solenoid 13 and tension spring 14) for switching the inlet guide 3 so that a top end part thereof is located above a tangent T on a nip 9 of the fixing device and the same top end part is located on the second position being lower than the first position, switching the inlet guide 3 to the first position before the top end of the sheet 5 enters into the nip 9 of the fixing device, and switching the inlet guide 3 to the second position after the top end of the sheet 5 entered into the nip 9 and before the trailing end of the sheet 5 reaches the nip 9.