A dielectric composition includes main phase grains and segregation grains. The segregation grains at least partly include Ba—Mg—Si—O segregation grains including Ba, Mg, Si, and O. Ba, Mg, and Si in the Ba—Mg—Si—O segregation grains constitute 70 parts by mol or more in total out of 100 parts by mol of a total of metal elements and Si in the Ba—Mg—Si—O segregation grains.