a tape recorder comprising a cassette tape compartment for detachably housing a first and second cassette tapes , a capstan for driving the first and second cassette tapes coaxially mounted thereon , a mode selector member for selecting the driving mode for the first and second cassette tapes , operation means for causing the second cassette tape to perform a first or a second function and causing the first cassette tape to perform the first function , a device for allowing the second cassette tape to achieve the first or second function , in response to operation of the operation means corresponding to the first or second function , when the second cassette tape - driving mode has been selected by the mode selector member , a device for allowing the first cassette tape to achieve the first function , in response to operation of the operation means corresponding to the first function , when the first cassette tape - driving mode has been selected by the mode selector member , and a function blocking device for hindering the first cassette tape from achieving the second function when the operation means corresponding to the second function is operated in the first cassette tape - driving mode selected by the mode selector member .