Multilayer film and wound body

A long-length multilayer film comprising a long-length optical film and a long-length protective film that is releasable from the long-length optical film, wherein

• the optical film has two major opposing surfaces including a first major surface proximal to the protective film and a second major surface distal to the protective film,
• the second major surface of the optical film has a three-dimensional center-line average roughness R1,
• the protective film has two major opposing surfaces including a first major surface proximal to the optical film and a second major surface distal to the optical film,
• the second major surface of the protective film has a three-dimensional center-line average roughness R2,
• the three-dimensional center-line average roughness R1 of the second major surface of the optical film, the three-dimensional center-line average roughness R2 of the second major surface of the protective film, a tensile elastic modulus M1 in a lengthwise direction of the optical film, and a tensile elastic modulus M2 in a lengthwise direction of the protective film satisfy all of the relationships of the following formulae (1) to (6):
• 0.01 μm≤R1≤0.05 μm (1),
• 0.01 μm≤R2≤0.2 μm (2),
• 1,500 MPa≤M1≤3,000 MPa (3),
• 2,500 MPa≤M2≤6,000 MPa (4),
• 1.0≤R2/R1≤5.0 (5), and
• 1.0≤M2/M1≤3.0 (6)
• the optical film is a multilayer film having a layer structure of ‘b’ layer/‘a’ layer/‘b’ layer,
• the ‘a’ layer is a layer formed from a resin containing a polystyrene-based polymer, and
• the ‘b’ layer is a layer formed from a resin containing a poly(methyl methacrylate) polymer.