In this study, an attempt was made to approximate the main characteristic values of Bi0.5(Na0.78K0.22)0.5TiO3 (= BNKT) depending on the content of Fe2O3 additives, aiming to approach the values of lead(Pb) piezoelectric ceramic materials (PZT). Specifically, when the piezoelectric coefficient (d33) value of lead(Pb) piezoelectric ceramic material (PZT polycrystalline ceramic powder) is 300[pC/N] or higher, it is applied for hard purposes such as ultrasonic welding machines and cleaning machines, and when it exceeds 330[pC/N], it is applied for soft purposes like piezoelectric sensors. In this study, research and development were conducted for devices with a piezoelectric coefficient (d33) of 300[pC/N] or more for actuators. For this purpose, K+ exceeding 0.02 to 0.12 mol% was added to (Na0.78K0.22)0.5Bi0.5TiO3 to analyze structural changes due to K+ excess, and (Na0.78K0.22)0.5Bi0.5TiO3 + 8mol% K2CO3 Ti4+ was substituted with Fe3+ to manufacture lead-free piezoelectric materials. As a result, ceramics with Fe3+ substitution at x = 0.0075 yielded an average value of d33 = 315[pC/N]. Furthermore, for ceramics with Fe3+ substitution at x = 0.0075, the average values of maximum polarization (Pmax), residual polarization (Prem), and coercive field (Ec) were found to be 39.63 μC/cm2, 30.45 μC/cm2, and 2.50 kV/mm, respectively. The reliable characteristic values obtained from the research results can be applied to linear actuator components (such as the zoom function of mobile cameras, LDM for skin care, etc.) and ultrasonic vibration components.