Abstract: The present invention relates to a process for preparing isoflavone aglucone using Rhodotorula glutinis, more specifically, to a novel Rhodotorula glutinis strain (KCCM-10172) which can be isolated from fermented soybeans and has a good ability to convert into isolfavone aglucone, and a process for preparing isoflavone aglucone using the said strain which comprises culture for 30-54 hours in a condition of pH 4.0-8.0 and 25-35° C. using an extract from soybeans or germs of soybeans as a medium and control of content of dissolved oxygen to produce isoflavone containing aglucone of a purity of 90% or more.