Jim Beloff (born December 25, 1955) is an American musician. He is a leading proponent of the ukulele. After working in the music industry in Los Angeles, he discovered the ukulele and became an advocate of the instrument. He established Flea Market Music, publisher of the Jumpin' Jim's ukulele songbook series. Beloff's songbooks and instructional books (arranged by him and other well-known ukulele players), DVDs and promotion and marketing of his family's Fluke and Flea ukuleles have contributed to the popularity of the instrument. He is also a singer-songwriter and has recorded several solo CDs as well as two with his wife, Liz.