In a remote control device for a vehicle including: a portable transmitter configured to repeatedly transmit a signal for giving an instruction to activate an activation device mounted in a vehicle, in response to an operation of a manipulator which is performed continuously for a predetermined time or more; and a vehicle-side receiver provided in the vehicle to activate the activation device based on the signal transmitted from the portable transmitter, the portable transmitter transmits a first signal including a data frame having at least an ID code, a function code determining an action of the activation device, and a first error detection code and then repeatedly transmits a second signal, and a data frame of the second signal having the same function code as that of the first signal and a second error detection code generated based on the function code and the data frame of the first signal.