To provide a simple mat that is waterproof and moistureproof, cheaper than a urethane foam one, can be easily incinerated, suited for use in an evacuation site at a disaster, using a plastic foamed sheet having cushioning capability and an insulating property.

The simple mat is made by separately folding a three-layer plastic foamed sheet (1) made up of a plastic cap film (11) provided with many protrusions, a flat plastic back film (12) pasted to the bottom of the protrusions, and a flat plastic liner film (13) pasted to the series of tops of the protrusions in an opposite direction at a fixed interval to form corrugates of a fixed thickness. Adjacent sides of the plastic foamed sheet are bonded by an adhesive (2) in parts of the corrugates near the folding lines.