It is an object of the present invention to provide a ferroelectric capacitor which maintains high ferroelecticity. A silicon oxide layer 2, a lower electrode 12, a ferroelectric layer 8 and an upper electrode 10 are formed on a silicon substrate 2. The lower electrode 12 is formed by an alloy layer made of iridium and platinum. The alloy layer of the lower electrode 12 can be formed under appropriate lattice constant correspond with a kind and composition of the ferroelectric layer 8. So that, a ferroelectric layer having excellent ferroelectricity can be obtained. Also, it is possible to prevent vacancy of oxygen in the ferroelectric layer 8.