An installation error detection apparatus of an onboard camera includes: an input portion that receives a photographed image; a storage portion that stores position information of a feature point of the vehicle; a feature point detection portion; a determination portion that determines whether the installation position of the onboard camera is the proper position; and a notification portion that informs installation defect of the onboard camera. The notification portion calculates the installation position of the onboard camera required to minimize the deviation amount and corrects the photographed image by the onboard camera. The notification portion detects the feature point and calculates a similarity degree of the position of the feature point and the position information. The notification portion determines the installation defect of the onboard camera and informs the installation defect. The notification portion determines that a vehicle body is deformed and informs the vehicle body being deformed.