a heater portion of 30 cm under a gas flow containing oxygen by 30 and nitrogen by 70 and having a relative humidity of 80 at 25 u00b0 c with a flow speed of 20 cm sec sintering step and was heat treated for 5 minutes at 650 u00b0 c in the same atmosphere sintering step after the coating and the heating were repeated three times a sintering was executed for 40 minutes at 700 u00b0 c in the above mentioned tubular oven and in a gaseous atmosphere containing oxygen by 30 and nitrogen by 70 and having a relative humidity of 75 at 25 u00b0 c sintering step followed by a cooling to the room temperature in the same humidity atmosphere cooling step to obtain a piezoelectric element of the present invention fig5 an analysis of an intermediate portion of the piezoelectric film provided a metal composition pb 1 0 zr 0 52 ti 0 48 the film thickness after coating and sintering three times was as follows on a substrate similar to that in the examples 1 4 each of the coating liquids obtained in the preparation examples 2 and 5 was spin coated and was dried for 5 minutes at 100 u00b0 c in the air having a relative humidity of 50 at 25 u00b0 c drying step it was then heated for 20 minutes at 300 u00b0 c in a tubular oven of a diameter of 5 cm and a length of 100 cm including a heater portion of 30 cm in a gaseous atmosphere containing oxygen by 30 and nitrogen by 70 and having a relative humidity of 90 at 25 u00b0 c sintering step after the coating and.