A modular floor mat unit which can be used individually or in combination with adjoining floor mat modules to provide an elevated surface which insulates personnel or materials from the floor surface. The floor mat is a unitary structure comprised of a tread surface integrally attached to the top edges of interconnected flanges which form a support frame. A plurality of drainage openings in the tread surface allow liquids and other substances to be removed from the tread surface to the underlying floor and also ventilate the area beneath the mat. Unitary traction plugs fabricated from a flexible resilient material protrude above and below the floor mat to provide traction and prevent slippage. A plurality of finger elements having inclined top surfaces and detent interlock devices protrude from all sides of the floor mat to provide both an inclined threshold surrounding the mat and means for interlocking adjacent mat modules to form a larger mat area.