We present the results of C^18^O observations by the Nobeyama Millimeter Array toward dense clumps with radii of ~0.3pc in six cluster-forming regions including massive (proto) stars. We identified 171 cores, whose radius, line width, and molecular mass range from 0.01 to 0.09pc, 0.43 to 3.33km/s, and 0.5 to 54.1M_{sun}_, respectively. Many cores with various line widths exist in one clump, and the index of the line width-radius relationship of the cores and the parental clump differs from core to core in the clump. This indicates that the degree of dissipation of the turbulent motion varies for each core in one clump.