To provide a roller holding unit which is detachable by a relatively light force.

The roller holding unit 20 comprises a holding block 31 for holding a bearing 24 of a roller 22, a rod member 33 inserted into a rod engaging block 32, a shaft end holding member 34 fixed to the member 33 and a spring pressure regulating member 35 retractably engaged with the member 33, and a spring member 36 mounted between the member 34 and the member 35. In this unit, the roller 22 is held by pressing of the member 34 according to an energizing force of the member 36. When the roller is attached and detached, the member 35 is first moved, an extending range of the member 36 is increased, and hence the force of the spring is weakened. Thereafter, the member 33 is pulled against a spring pressure, and the member 34 is retracted from a contact position of the bearing 24.