A vehicular panel structure includes a panel, a reinforcement disposed inward of the panel in a vehicle, and mastic that bonds the panel and the reinforcement to each other. The reinforcement is provided with a body portion constituting a middle portion in a longitudinal direction and having a linear expansion coefficient smaller than the linear expansion coefficient of the panel, a connection portion constituting an end portion in the longitudinal direction, and a joining portion allowing the body portion and the connection portion to be joined to each other by a thermosetting adhesive and a fastener. A long hole portion is disposed in the reinforcement and is formed in either the connection portion or the body portion. The fastener is inserted into the long hole portion.