1-3-µm-thick (K,Na)NbO 3 films were epitaxially grown on SrRuO 3 /(001)SrTiO 3 substrates by the pulsed laser deposition using (K x Na 1%x )NbO 3 targets. Energy dispersive X-ray spectroscopy analysis showed that the film K content was about 10% lower than the target K content x at x = 0.1-0.8, and the (K + Na)/Nb atomic ratio was 0.8-1.0. Reciprocal space mapping of the films revealed that the films were epitaxially grown at x = 0-0.7, and the crystal system was altered with increasing K content. Ferroelectric polarization-electric field loops were observed at x = 0-0.9, with the maximum remanent polarization of >40 µC/cm 2 at x = 0.5. The remanent polarization vs K content profile was discussed with crystal structure analyses.