There are disclosed a piezoelectric actuator which can obtain large displacement at low voltage, which is small-sized and lightweight, and whose manufacture cost is low, and a small-sized lightweight information storage apparatus in which the piezoelectric actuator is incorporated, and which is provided with a small inertia moment during head driving and a high recording density. A piezoelectric actuator 200 includes a center body 200a and two spiral arms 200b, and two arms 200b are entirely in rotation symmetry and nonlinear symmetry.