With hot filament chemical vapor deposited samples having a diamond nature and a graphitic carbon nature, we have investigated the correlation between the field emission properties and spatial distribution of emission sites. The field emission properties are substantially improved with increasing the nondiamond carbon content. It is confirmed that emission sites are mainly observed at the edge when a small amount of nondiamond carbon is existed in diamond films while emissions occur at the center as well as the edge with increasing the nondiamond carbon content. On the other hand, the spatial distributions of emission sites for graphitic carbon films are not related to the nondiamond carbon content but to the thickness and distribution of the sheet,