High-speed, image-sensor visible light communication using rolling shutter has been studied. Symbol synchronization method by sequential estimation is applied to the line scan sampling using the rolling shutter of the image sensor and achievable symbol rate is simulated. Over 1400 symbols per second can be realized by the symbol synchronization at the frame rate of 30 fps with a QVGA screen. Acceptable symbol rate difference range is also simulated for the image-sensor used in a smartphone. Besides, received symbol pattern of the 30-fps image sensor was measured at different symbol rates to confirm the simulation results.