An angle at which an intensity becomes maximum in a light distribution of light emitted from a center of a light emitting surface of a surface illumination device is in a range of 90 or more to less than 0 in a plane including a vertical axis and perpendicular to the light emitting surface, in a case where an axis passing through the center of the light emitting surface and perpendicular to the floor surface is defined as the vertical axis, and in the plane, a direction extending from the center of the light emitting surface toward the floor surface is defined as 90, a direction extending from the center of the light emitting surface toward a side opposite to the floor surface is defined as +90, and a direction orthogonal to the light emitting surface is defined as vertical 0.