The invention relates to a biologically degradable heat-insulating material. In order to provide an improved biologically degradable heat-insulating material, the invention proposes a biologically degradable heat-insulating material containing 50 to 90 wt. % of a cellulose and/or wood fibre having an average fibre diameter of 1 mm or less and an average fibre length of 20 mm or less, 2 to wt. % of a flame-retardant agent as well as 5 to 30 wt. % of a biologically degradable binder in the form of bico fibres having an average fibre diameter of 1 mm or less and a fibre length of 20 mm or less, wherein the density of the heat-insulating material is 30 to 300 kg/m.sup.3.