A vehicle controller includes: a determination unit configured to determine a preparatory speed of a vehicle in a merging lane based on a relative speed between a first main lane vehicle traveling on a main lane and the vehicle, the first main lane vehicle being detected by a front sensor of the vehicle; a preparation unit configured to adjust speed of the vehicle such that the speed of the vehicle coincides with the preparatory speed; and a merging control unit configured to merge the vehicle into the main lane from the merging lane based on at least a detection result of a side sensor of the vehicle and the speed of the vehicle, when the vehicle is in a situation where the main lane vehicle is recognizable based on the detection result of the side sensor, after the preparation unit starts speed adjustment of the vehicle.