Two biopolymers produced from submerged culture of edible mushrooms were directly observed by atomic force microscopy. Biopolymers were deposited on mica from dilute aqueous solution and imaged in air through a thin layer of adsorbed water and their hydrated structures were observed by a tapping mode. A single biopolymer molecule obtained from Cordyceps militaris was typical of a rod-like structure with bending point, which can form intra- and inter-molecular supercoils. In contrast, the image for low molecular weight biopolymer from Paecilomyces sinclarii is typical of a branched structure in which more extensive interaction leads to the formation of network-like matrix.