Abstract: Automated driving is an emerging technology in which a car performs the tasks of recognition, decision making, and control. Recognizing surrounding vehicles is vital in generating the trajectory of an ego-vehicle. This paper focuses on detecting a turn signal information as one of the driver’s intention for surrounding vehicles. This information helps to predict the driver’s behavior in advance especially as instances of lane change and turns at an intersection. Using their intension, the automated vehicle is able to generate a safety trajectory before the driver’s behavior changes. The proposed method recognizes the turn signal of the target vehicle using a mono-camera. It detects the lighting state using Convolutional Neural Network, and then calculates a flashing frequency using Fast Fourier Transform.