Provided is an illumination type key sheet which efficiently diffuses local heat generated by a mounted element on a board and which makes an EL member relatively free from generation of unevenness in luminance. An illumination type key sheet (3) is equipped with a graphite sheet (6) which diffuses heat in a surface direction. Thus, if a semiconductor device (11) on a board (4) generates heat, it is possible to prevent local heating of an EL sheet (5) by the graphite sheet (6), making the EL sheet (5) relatively free from generation of unevenness in luminance. At the same time, it is possible to prevent occurrence of problems, such as malfunction and failure, due to heat storage of the semiconductor device (11). As compared with other materials, the graphite sheet (6) exhibits high heat conductivity allows efficient heat diffusion, and is lightweight. Thus, it can meet the demand for a reduction in a weight of portable electronic apparatuses.