<p>This study developed and introduced the wave energy conversion analysis program (WECAN-POWER), which estimates the initial annual power generation of floating body-type wave energy converter (WEC). The WECAN-POWER program takes into account the impact of nonlinear motion of floating body-type WEC devices caused by incident waves. It also considers both the optimal power take-off (PTO) damping at the device’s natural frequency and the optimal PTO damping for each incident wave. Furthermore, rather than assuming the efficiency of the generator and power conversion system (PCS) with fixed values, the program applies a more practical approach by normalized mechanical energy and rated capacity to more accurately represent the efficiency of the generator and PCS. The WECAN-POWER program allows designers of floating body-type WEC devices to more realistically estimate the initial annual power generation and aims to contribute to the promotion of wave energy converter adoption.</p>