A keyboard apparatus has a base component arranged under key switches. The base component has an embossed portion. A cooling material is filled into the embossed portion. The embossed portion may be formed continuously between the key switches along the length of key rows over substantially the entire length from the left end to the right end of the rows. On the base component, a membrane sheet having contact point portions corresponding to the key switches may be arranged. The membrane sheet may have a heat dissipation hole at a part opposing the embossed portion.