To provide a readily producible cellulose/polyolefin-based composite material having excellent balance among physical properties and excellent linear expansion characteristics.

The cellulose/polyolefin-based composite material comprises (A) a cellulose nonwoven fabric, (B) a modified polyolefin having functional groups, and (C) a polyolefin. The method for producing the cellulose/polyolefin-based composite material comprises dipping or coating (A) the cellulose nonwoven fabric with (B) the modified polyolefin having the functional groups, and then laminating (C) a polyolefin thereto.