A homomorphic encryption apparatus and method are disclosed. The homomorphic encryption apparatus includes one or more processors, and memory storing instructions configured to, when executed by the one or more processors, cause the one or more processors to receive a blind rotation key for performing a blind rotation operation and receive an operand ciphertext of the blind rotation operation, generate a first ciphertext by performing addition of a polynomial representation based on the blind rotation key and the operand ciphertext, and generate a target ciphertext by performing key switching and accumulative multiplication based on the first ciphertext.