To provide a tapered roller bearing and a differential device inexpensively, in which seizure hardly occurs owing to poor lubrication even under the condition that an flow-in amount (amount supplied) of a lubricating oil is small.

In a front side which is a supply side of the lubricating oil in the tapered roller bearing 10, an outer peripheral surface 11b of an inner ring 11 is formed extendedly in a straight shape along the outer peripheral surface of the tapered roller bearing 13 to open. A minor diameter end of a retainer 14 is radially truncated in a straight shape to open. In the back surface 11c side of an inner ring 11 to be a discharge side of the lubricating oil, a snap ring 40 for a hole is fastened in the inner peripheral surface of the extended portion 12a of an outer ring 12. An inner diameter D2 of the snap ring 40 for the hole is formed larger than an outer diameter D1 of the large flange 11a of the inner ring 11.