Fixing member and heat fixing device

A heat fixing device comprising:

• a heating member;
• and
• a pressurizing member arranged to face the heating member,
• wherein the heating member includes a substrate and an elastic layer on the substrate,
• the elastic layer containing a rubber and fillers dispersed in the rubber, assuming that five of binarized images each of which has a size of 150 μm×100 μm on any positions of a first section in thickness-peripheral directions of the elastic layer, and five of binarized images each of which has a size of 150 μm×100 μm on any positions of a second section in thickness-axial directions of the elastic layer are obtained, in each of the binarized images, the fillers are represented as white, and the rubber is represented as black,
• among the fillers in the binarized images, fillers having a circle-equivalent diameter of 5 μm or more are defined as large-particle diameter fillers, and fillers having a circle-equivalent diameter of less than 5 μm is defined as small-particle diameter fillers,
• and assuming that area ratios (%) of which a total areas of the large-particle diameter fillers with respect to the respective binarized images' areas are calculated, and area ratios (%) of which a total areas of the small-particle diameter fillers with respect to the respective binarized images' areas are calculated,
• an average value of the area ratios of the large-particle diameter fillers is 20% or more and 40% or less, and the large-particle diameter fillers have an average array degree fL of 0.00 or more and 0.15 or less,
• an average value of the area ratios of the small-particle diameter fillers is 10% or more and 20% or less,
• the small-particle diameter fillers have an average array degree fS of 0.20 or more and 0.50 or less, and
• the small-particle diameter fillers have an average array angle ΦS of 60° or more and 120° or less.