A vehicle input-operation assistance device includes: a traveling state detection section that detects a traveling state of a vehicle; an operation state detection section that detects an operation state of an operation member gripped by an occupant during operation; a support section that is capable of being stowed in an interior component of the vehicle, and that is capable of projecting from the interior component to a support position where the support section is capable of supporting an elbow of the occupant when the occupant is operating the operation member; and a controller that determines whether or not the elbow of the occupant operating the operation member needs to be supported based on information detected by the traveling state detection section and the operation state detection section and, in cases in which support is determined to be needed, controls the support section to project to the support position.