We report the magnetoresistance of ScSb, which is a semimetal with a simple rocksalt-type structure. We found that the magnetoresistance reaches ∼28000% at 2 K and 14 T in our best sample, and it exhibits a resistivity plateau at low temperatures. The Shubnikov–de Haas oscillations extracted from the magnetoresistance data allow the full construction of the Fermi surface, including the so-called α3 pocket which has been missing in other closely related monoantimonides, and an additional hole pocket centered at Γ. The electron concentration (n) and the hole concentration (p) are extracted from our analysis, which indicates that ScSb is a nearly compensated semimetal with n/p≈0.93. The calculated band structure indicates the absence of a band inversion, and the large magnetoresistance in ScSb can be attributed to the nearly perfect compensation of electrons and holes, despite the existence of the additional hole pocket.