A piezoelectric thin film element includes a bottom electrode, a piezoelectric layer and a top electrode on a substrate. The piezoelectric layer includes as a main phase a perovskite-type oxide represented by (NaxKyLiz)NbO3 (0≦x≦1, 0≦y≦1, 0≦z≦0.2, x+y+z=1), and the bottom electrode includes a surface roughness of not more than 0.86 nm in arithmetic mean roughness Ra or not more than 1.1 nm in root mean square roughness Rms.