An undercover structure for a vehicle, comprising an undercover that is to cover a battery pack from below, the battery pack being located below a floor assembly of a vehicle, the undercover having a front panel and a rear panel located on a vehicle rear side of the front panel, a rear end region of the front panel in a vehicle front-rear direction and a front end region of the rear panel in the vehicle front-rear direction being coupled, wherein: the front panel includes a first engaging portion located in the rear end region; the rear panel includes a second engaging portion located in the front end region; the first engaging portion and the second engaging portion are configured to engage with each other; the first engaging portion includes a rear side opening formed so that the second engaging portion can be inserted in a direction from a vehicle front side toward a vehicle rear side; the first engaging portion includes a top surface portion that is offset upward with respect to a body portion of the front panel arranged in a vehicle horizontal direction; characterized in that the first engaging portion includes a lateral side surface portion that is located at a lateral end of the first engaging portion in a vehicle width direction and that rises upward from the body portion of the front panel to a lateral end of the top surface portion in the vehicle width direction; the rear side opening is located at a rear end of the top surface portion in the vehicle front-rear direction and at a rear end of the lateral side surface portion in the vehicle front-rear direction; and the second engaging portion has a lateral edge located on one side of the second engaging portion in the vehicle width direction so that the lateral edge can be in contact with the lateral side surface portion of the first engaging portion of the front panel in a temporary holding state of the front and rear panels (20,30). the undercover having a front panel and a rear panel located on a vehicle rear side of the front panel, a rear end region of the front panel in a vehicle front-rear direction and a front end region of the rear panel in the vehicle front-rear direction being coupled, wherein: the front panel includes a first engaging portion located in the rear end region; the rear panel includes a second engaging portion located in the front end region; the first engaging portion and the second engaging portion are configured to engage with each other; the first engaging portion includes a rear side opening formed so that the second engaging portion can be inserted in a direction from a vehicle front side toward a vehicle rear side; the first engaging portion includes a top surface portion that is offset upward with respect to a body portion of the front panel arranged in a vehicle horizontal direction; characterized in that the first engaging portion includes a lateral side surface portion that is located at a lateral end of the first engaging portion in a vehicle width direction and that rises upward from the body portion of the front panel to a lateral end of the top surface portion in the vehicle width direction; the rear side opening is located at a rear end of the top surface portion in the vehicle front-rear direction and at a rear end of the lateral side surface portion in the vehicle front-rear direction; and the second engaging portion has a lateral edge located on one side of the second engaging portion in the vehicle width direction so that the lateral edge can be in contact with the lateral side surface portion of the first engaging portion of the front panel in a temporary holding state of the front and rear panels (20,30). the front panel includes a first engaging portion located in the rear end region; the rear panel includes a second engaging portion located in the front end region; the first engaging portion and the second engaging portion are configured to engage with each other; the first engaging portion includes a rear side opening formed so that the second engaging portion can be inserted in a direction from a vehicle front side toward a vehicle rear side; the first engaging portion includes a top surface portion that is offset upward with respect to a body portion of the front panel arranged in a vehicle horizontal direction; characterized in that the first engaging portion includes a lateral side surface portion that is located at a lateral end of the first engaging portion in a vehicle width direction and that rises upward from the body portion of the front panel to a lateral end of the top surface portion in the vehicle width direction; the rear side opening is located at a rear end of the top surface portion in the vehicle front-rear direction and at a rear end of the lateral side surface portion in the vehicle front-rear direction; and the second engaging portion has a lateral edge located on one side of the second engaging portion in the vehicle width direction so that the lateral edge can be in contact with the lateral side surface portion of the first engaging portion of the front panel in a temporary holding state of the front and rear panels (20,30).