Abstract: A method for designing a piezoelectric element unit, a ultrasonic element having the piezoelectric element manufactured using the method, a method for manufacturing the ultrasonic element, and an acoustic pressure focusing device having the ultrasonic element are provided. In the method for designing a piezoelectric element unit, a target position and a target distance are selected. A basic information of a piezoelectric element base material is inputted. Each of a plurality of grids is grouped into a unit grid group. A size of an output acoustic pressure outputted at each unit grid group is calculated. The unit grid group outputting the output acoustic pressure included in a range of a reference acoustic pressure among a plurality of the unit groups is decided. The plurality of ring patterns being concentric is determined based on a pattern shape information.