To provide a daylighting board material which facilitates the construction and is superior in sound insulating performance, heat insulating performance, and shock resistance.

A building board material 50 is constituted of a board main body part 51 which are formed by superposing two resin rectangular plates 61, 62 via a lot of mutually parallel ribs 63 crossing at right angles with the respective plates and extended in the length direction of the plates, and a pair connecting parts 52a, 52b which is formed in both side surface parts 51a, 51b in parallel to the ribs 63 of the board main body part 51 and connect a plurality of the board main body parts 51 approximately flush in the adjacent to each other.