An efficient low-cost method of proteoglycan recovery from natural resources. There is provided a process for producing proteoglycan, comprising the steps of immersing a biological sample containing proteoglycan in an alkali solution of 0.0025 to 0.1 N and recovering the solution after the immersion. As compared with the conventional extraction method, proteoglycan can be recovered in unaltered undecomposed form easily within a short period of time, thereby attaining substantial reduction of proteoglycan production cost. Further, proteoglycan highly useful in industry can be recovered from wasted portions of fin, feather, mammal, etc. having mainly been discarded, thereby contributing toward effective utilization of industrial waste and reduction of the volume of industrial waste per se.