In order to shorten the firing time for sintering textured (K,Na)NbO3 system ceramics, the fabrication method of the single-step molten salt synthesis for preparing platelike NaNbO3 single-crystal particles was improved. An uneven shape was formed on the surfaces of platelike NaNbO3 single-crystal particles obtained by single-step molten salt synthesis in the mixed salts of KCl and NaCl. Using these single-crystal particles as the templates, textured (K,Na)NbO3 ceramics were fabricated. The sinterability of the textured ceramics and their piezoelectricity were compared between two kinds of templates synthesized in the mixed salt and in the conventional NaCl salt. The diffusivity of K atoms into these templates from the matrix powder of (K,Na)NbO3 during firing was also compared.