A vehicular antenna device (1, 81) configured to be attached to an attachment portion of a vehicle, the vehicular antenna device comprising: - an antenna portion having an antenna element; and - a frame (8, 82) accommodating a heat generation member, wherein - the frame includes a first space portion (31, 84) having a cylindrical shape and defining a first space, the first space portion being exposed to an outside air in a condition where the vehicular antenna device is attached to the vehicle, - the heat generation member is located along a second surface of the frame that is a reverse side of a first surface defining the first space, - the antenna portion is an antenna substrate having a flat plate shape, - the antenna element is located on an opposite side of the first space opposite from the heat generation member, - the heat generation member is mounted on a control board, - the frame includes a second space portion (37, 85) configured to accommodate a substrate connection portion electrically connecting the antenna substrate and the control board, - the second space portion is located in the first space, - the frame includes an antenna attachment portion that is an upper part of the frame and a control board accommodation portion that is a lower part of the frame, - the first space portion (31, 84) is formed by an upper side wall, a left side wall, a right side wall, and a bottom wall of the antenna attachment portion, - the antenna attachment portion includes a column wall connecting the upper side wall and the bottom wall, and - the second space portion (37, 85) is defined by an inner surface of the column wall to have a cylindrical shape. - an antenna portion having an antenna element; and - a frame (8, 82) accommodating a heat generation member, wherein - the frame includes a first space portion (31, 84) having a cylindrical shape and defining a first space, the first space portion being exposed to an outside air in a condition where the vehicular antenna device is attached to the vehicle, - the heat generation member is located along a second surface of the frame that is a reverse side of a first surface defining the first space, - the antenna portion is an antenna substrate having a flat plate shape, - the antenna element is located on an opposite side of the first space opposite from the heat generation member, - the heat generation member is mounted on a control board, - the frame includes a second space portion (37, 85) configured to accommodate a substrate connection portion electrically connecting the antenna substrate and the control board, - the second space portion is located in the first space, - the frame includes an antenna attachment portion that is an upper part of the frame and a control board accommodation portion that is a lower part of the frame, - the first space portion (31, 84) is formed by an upper side wall, a left side wall, a right side wall, and a bottom wall of the antenna attachment portion, - the antenna attachment portion includes a column wall connecting the upper side wall and the bottom wall, and - the second space portion (37, 85) is defined by an inner surface of the column wall to have a cylindrical shape.