An optical film producing method, comprises steps of: extruding a melted material including a melted cellulose ester resin from a casting die by using an extruding device; forming a film by pressing the extruded melted material between a first rotating member and a second rotating member; and winding up the formed film, wherein the following formulas are satisfied: 30\xb0 C. The multi-clock module includes a multi-clock generator that is configured to generate a clock signal with a variable frequency based on a channel setting. The virtual disks of the virtual storage array are mapped to physical data storage at the data center and accessed via a WAN using storage block-based protocols. A user at the navigation terminal is made to refer to this evaluation information and to select a desired recommended route from the plurality of recommended routes.