To provide a planar luminaire which assures constant luminance without causing degradation in brightness.

First and second rod-like light guides 4a and 4b with refractive index n1 of 1.49 are bonded together as one body using an adhesive 32 of translucent material provided at a first gap 30a except for a groove 15. The refractive index (n) of the adhesive 32 is 1.3<n<(n1-0.1), which is close to a refractive index of n1 of the first and the second rod-like light guides 4a and 4b. Since bonding is made using the adhesive 32, no air layer whose refractive index is significantly different from the rod-like light guide 4 is present between the adhesive 32 and the first and the second rod-like light guides 4a and 4b. So, the difference of refractive index at an interface 31 becomes smaller to reduce amount of reflected light, or loss, at the interface 31, resulting in increased amount of transmitted light for increased brightness of a plate-like light guide 3.