A ceramic dynamic-pressure bearing includes a first member 14 having a cylindrical outer surface and a second member 15 having a cylindrical reception hole formed therein. The first member 14 is inserted into the reception hole. A radial dynamic-pressure gap is formed between the inner surface of the reception hole of the second member 15 and the outer circumferential surface of the first member 14. The first member 14 and the second member 15 are formed of an alumina ceramic which contains an Al component in an amount of 90 99.5% by mass as reduced to Al.sub.2O.sub.3 and an oxide-type sintering aid component in an amount of 0.5 10% by mass as reduced to an oxide thereof. The thrust dynamic-pressure gap definition surface of the second member which faces the thrust plate has a flatness of not greater than 3 .mu.m or the thrust dynamic-pressure gap definition surface of the thrust plate which faces the second member has a flatness of not greater than 3 .mu.m. Also disclosed is a hard disk drive having a motor including a motor rotation output section having the ceramic dynamic-pressure bearing.