[Objective] The color is one of the important factor for commercial value of edible mushroom. Pleurotus cornucopiae is edible mushroom, naturally distributed in the northern part of Japan. Due to its beautiful yellowish color, P. cornucopiae is sometimes called as “Golden-Shimeji”. The unique flavor of this mushroom also help to enhacement its commercial value and the consumption of this mushroom has gradually increased. The yellow color of this mushroom is resistant against high temperature because the color is not diminished after deep-frying. These facts suggest that the structure and biosynthesis of this yellow color is very interesting. However, the report concerning about these profiles are none at all. In the present study, we tried to isolate yellow pigment from P. cornucopiae fruit body and some properties of the pigments were also investigated. [Methods and Results] The fruit body of P. cornucopiae was kindly given from Tanaka Machinery Corporation and kept in the freezer (-20°C) until use. The fruit body was homogenized with twice amount of ice cold distilled water with a mixer and subsequently filtered to be crude pigment solution. According to the result of ultra filtration by CentriPrep YM-10, molecular weight of the pigment was under 10,000. The resultant filtrate of YM-10 was concentrated by lyophilization and subsequently subjected to size exclusion chromatography (SEC) by Sephadex LH-20. Two different pigment fractions, brown and yellow, were obtained from SEC separation. According to the retention time of HPLC analysis with TSKgel G2500PWXL, the molecular weights of these two pigments are larger than size exclusion limit (Ca. 5,000). Moreover, detectable spot with ninhydrin reagent on thin layer chromatography (TLC) analysis suggest that these pigments are guessed as peptide compounds. In addition, no color changes were observed after heating for 20 min at 100℃.