Vehicle cruise control device and cruise control method

A vehicle cruise control device in which an imaging device for imaging a region in front of an own vehicle is mounted, the vehicle cruise control device comprising:

• a memory;
• a processor communicable to the memory;
• and
• a set of computer-executable instructions stored on the memory that cause the processor to implement:
• recognizing a lane boundary that defines an own lane that is a travel lane of the own vehicle on the basis of an image acquired by the imaging device;
• and
• performing cutting-in determination and deviation determination with regard to a forward vehicle traveling ahead of the own vehicle, in which the forward vehicle traveling on an adjacent lane adjacent to the own lane is determined to be a cutting-in vehicle that cuts into the own lane, and the forward vehicle traveling on the own lane is determined to be a deviating vehicle that deviates from the own lane, on the basis of a relative position with respect to a recognized boundary that is the lane boundary recognized by the processor in a vehicle width direction of the forward vehicle.