Provided is an apparatus for providing obstacle information and reliability information to vehicle based on information received from roadside units. The apparatus includes a communication module that receives obstacle information from multiple roadside units, each roadside unit including multiple sensors for detecting obstacles within a predetermined field of view. A reliability judgement unit in the apparatus determines a reliability of the received obstacle information to output a reliability value based on a number of roadside units detecting a same obstacle, a number of sensor of one roadside unit detecting a same obstacle, and a difference value of detection of the same obstacle between different roadside units or different sensors.