In a lamp device 12 using a GX53-type cap 31 and also using an LED 56 as a light source, there is regulated an appropriate configuration of a metallic cover 32. A cap 31 and a lighting device 36 are arranged on an upper surface side of the metallic cover 32, and a substrate 33 on which the LED 56 is mounted is arranged on a lower surface side thereof. The metallic cover 32 has an approximately cylindrical shape with a maximum outer diameter D of 80 to 150 mm, a height H of 5 to 25 mm, and 2π (D/2) H/W, that is, an area of the outer peripheral surface per gross input power W to the lamp device 12 being in a range of 200 to 800 mm2/W. The gross input power W is 5 to 20 W.