An actuator includes a fired ceramic substrate having a space opened downward, a first electrode formed on the upper surface of the fired ceramic substrate above the space, a piezoelectric/electrostrictive body formed on the first electrode so that the volume changes with input and output of electric power, and a second electrode formed on the piezoelectric/electrostrictive body. The piezoelectric/electrostrictive body is composed of Pb(Zr1-xTix)O3 or (Li, Na, K) (Nb, Ta)O3 as a main component and contains crystals oriented along the direction of an electric field. In the actuator, the degree of orientation of the piezoelectric/electrostrictive body can be increased regardless of the orientation of the substrate on which the piezoelectric/electrostrictive body is formed.