A vehicle display device, includes: a curve information acquisition section configured to acquire information relating to a degree of curvature of a travel lane; a deceleration determination section configured to determine whether or not deceleration of a vehicle is required based on the degree of curvature of the travel lane and a vehicle speed; and a marking display section configured to, in a case in which deceleration is required, cause a display device to display a predetermined first marking superimposed along the travel lane at a display region inside a vehicle cabin.