Masako Shirasu (白洲正子, Shirasu Masako) (January 7, 1910 – December 26, 1998) was a Japanese author and collector of fine arts. Her husband was the diplomat Jirō Shirasu.
She was the daughter of a noble family which originally came from Satsuma.
She was the first known woman to perform a Noh play. She became an avid collector of Japanese antiques and published a large number of books on the subject. She was an expert especially on Japanese ceramics.
Their house Buaisō later became a museum. A special exhibition dedicated to her work and memory was organised by the Miho Museum and Nihon Keizai Shinbun in December 2000.