A dielectric composition including a complex oxide containing bismuth, zinc, and niobium, includes a crystal phase formed of the complex oxide and having a pyrochlore type crystal structure, and an amorphous phase. When the complex oxide is represented by a composition formula BixZnyNbzO1.75+δ, in which x, y, and z satisfy relations of x+y+z=1.00, 0.20≤y≤0.50, and 2/3≤x/z≤3/2.