Disclosed herein are an apparatus and method for virtualizing Input/Output (I/O) devices. The apparatus includes a hardware device control unit, a guest Operating System (OS) unit, a virtual machine monitor unit, and a host OS unit. The hardware device control unit controls the I/O devices of a terminal. The guest OS unit runs a guest OS via a virtual machine. The virtual machine monitor unit includes shared memory and an event channel, stores an instruction and data, and transfers the stored instruction and the data to a host OS. The host OS unit performs the operation of assigning the shared memory to the virtual machine monitor unit, the operation of generating the event channel, and an operation corresponding to the I/O instruction, stores the results of performance of the operations, and performs control so that the results of the performance of the operations are sent to the guest OS unit.