The object of the present invention is to provide the dielectric thin film having a main component including a oxynitride having excellent dielectric property, and a capacitance element including the dielectric thin film. A dielectric thin film comprising a main component comprised of an oxynitride expressed by a compositional formula of A a B b O o N n (a + b + o + n =5), wherein said "A" is one or more selected from the group consisting of Sr, Ba, Ca, La, Ce, Pr, Nd, and Na, said "B" is one or more selected from the group consisting of Ta, Nb, Ti, and W, and crystalline particles constituting said dielectric thin film are polycrystalline which are not oriented to a particular crystal plane orientation, and further the crystalline particles comprises columnar shape crystals.