We analyze the binary microlensing event MOA-2016-BLG-231 , which was observed from the ground and from Spitzer . The lens is composed of very low-mass brown dwarfs ( BDs ) with M _ { 1 } = 21 ^ { +12 } _ { -5 } M _ { J } and M _ { 2 } = 9 ^ { +5 } _ { -2 } M _ { J } , and it is located in the Galactic disk D _ { L } = 2.85 ^ { +0.88 } _ { -0.50 } { kpc } . This is the fifth binary brown dwarf discovered by microlensing , and the BD binary is moving counter to the orbital motion of disk stars . Constraints on the lens physical properties come from late time , non-caustic-crossing features of the Spitzer light curve . Thus , MOA-2016-BLG-231 shows how Spitzer plays a crucial role in resolving the nature of BDs in binary BD events with short timescale ( \lesssim 10 days ) .