To provide a web widening apparatus reducing the slipping between a web and a sleeve accompanying the enlargement and speed-up of a machine, and capable of ensuring the effects of widening and smoothing down of the web.

This web widening apparatus comprises a curved fixed axis metal 2, and a sleeve 3, which is supported on the fixed axis metal 2 and freely rotatable around the fixed axis 2; and the sleeve 3 is made to touch with a travelling web 20 to widen the width of the web 20. This web opening apparatus is provided with a suctioning exhausting unit, a suctioning hole 10 communicating te suctioning exhausting unit to the inside of the sleeve 3 is formed on the fixed axis metal 2, and plural air holes 12 for communication between the inside and outside of the sleeve 3 are formed on the entire peripheral surface of the sleeve 3.