The present invention provides a piezoelectric actuator that enjoys excellent practicality. The piezoelectric actuator includes a piezoelectric element (2) including a sheet of piezoelectric ceramic and electrodes formed at least part of the surface of the sheet of piezoelectric ceramic, and a holding member (4) holding the piezoelectric element (2). The piezoelectric at least one of the requirements (a) to (e) described below. (a) The bulk density shall be equal to or smaller than 5 g/cm3, and the Young's modulus Y11E calculated according to a resonance-antiresonance method shall be equal to or larger than 90 GPa. (b) The coefficient of thermal conductivity shall be equal to or larger than 2 Wm−1K−1. (c) The coefficient of thermal expansion shall be equal to or larger than 3.0 ppm/° C. over a temperature range from −30° C. to 160° C. (d) The pyroelectric coefficient shall be equal to or smaller than 400 μCm−2K−1 over the temperature range from −30° C. to 160° C. (e) The mechanical quality factor Qm calculated according to the resonance-antiresonance method shall be equal to or smaller than 50 over a temperature range from −30° C. to 80° C.