To provide a surface luminaire assuring efficient light utilization with no degradation in assembling characteristics.

First and second extension plates 23 and 24 are provided to an upper-side opposed plate 21 of a frame 15 by bending to provide a spring force toward the opposite side. The spring forces of the first and second extension plates 23 and 24 are used to pressurize a point-like light source 6 and a light guide 5. The clearances are eliminated between the point-like light source 6 and the first extension plate 23 as well as between the light guide 5 and the second extension plate 24 (in otherwords, the tolerance of a member is absorbed by pressing in), preventing occurrence of looseness for improved assembling characteristics. The point-like light source 6 and the light guide 5 are tightly fitted together to exclude the clearance between them, for improved efficiency in light utilization by the amount. The clearance which a conventional technology takes into account is not required, resulting in a compact frame 15 as well as the entire device, of high precision.