An oxygen storage material comprises a Ce—Zr-Ln-Ti-based composite oxide containing cerium (Ce), zirconium (Zr), a rear-earth element (Ln: excluding cerium), and titanium (Ti), wherein at least part of the rear-earth element and at least part of the titanium are solid-dissolved in a composite oxide of the cerium and the zirconium, and the Ce—Zr-Ln-Ti-based composite oxide has a composition expressed by the following chemical formula (1): Cea-xLnxZrb-yTiyOδ  (1), where a, b, x, and y are numbers satisfying conditions of a=0.4 to 0.6, b=0.4 to 0.6, x=0 to a (exclusive of x=0 and x=a), y=0 to 0.3 (exclusive of y=0), and a+b=1, and δ is a number of 1.7 to 2.2.