A support brace for a musical instrument such as a base trombone has a flexible band which is configured to be wrapped around a user's wrist and hand. The band has an upwardly extending first pocket which contains a first reinforcement member. Straps extend from the band and employ hook and loop fastener material to adjustably retain the band on the user's wrist and hand. An elliptical support knob extends outwardly from the band and is configured to receive and support a horizontal tube portion of the musical instrument. A first fastener with a head extends through the first reinforcement member and the band and is secured to the support knob, thereby joining the knob to the reinforcement member so that forces applied to the support knob are carried to the first reinforcement member. The instrument height can be adjusted by rotating and securing in place the elliptical support knob.