To provide a composite sheet having a plastic deformation property and an easily handleable shape keeping property, and a bag or a container with a self-standing property and a property for keeping a desired shape such as an opening state or the like of an opening part.

The composite sheet comprises (B) a sheet substrate reinforced by (A) a fibrous material of a thermoplastic resin with a return angle of 30 degree or less when it is bent to 90 degree. The shape keeping property is given to the composite sheet obtained by keeping the return angle on 90 degree bending in the range as the above.