Calcium titanate powder, method for producing same and external toner additive for electrophotography

A powder which is composed of particles that are mainly composed of calcium titanate having a perovskite crystal structure, and primary particles of which have a generally spherical shape and an average particle diameter within the range of from 20 nm to 100 nm (inclusive). This powder is produced by a method which comprises: the production of calcium titanate by subjecting a mixed liquid that contains a sugar, an alkali, a water-soluble compound containing calcium, and a compound which is obtained by deflocculating a hydrolysis product of a titanium compound with use of a monobasic acid to a high-pressure liquid-phase reaction that includes heating to a temperature of from 100° ° C. to 270° C. (inclusive),; and a subsequent calcium removal treatment.