A transmitter includes a controller, configured to generate a control voltage corresponding to a pattern of the change in an amount of light emitted wherein the pattern in which one of a plurality of amounts of light emitted occurs indicates a signal to be transmitted, and a reflector that reflects sunlight. The transmitter also includes a liquid crystal board that receives reflected light that is sunlight reflected by the reflector and transmits the signal to a receiver by changing the amount of light emitted toward the receiver according to the control voltage. The liquid crystal board changes the reflected light passing through rate to a high passing through rate when one of the plurality of the amounts of light emitted occurs, and changes the reflected light passing through rate to a low passing through rate when another one of the plurality of amounts of light emitted occurs.