We studied the propagation of interplanetary counterpart of coronal mass ejections (ICMEs) by using interplanetary scintillation (IPS) measurements of the Solar‐Terrestrial Environment Laboratory at 327MHz. In this study, we analyzed data of the solar wind disturbance factor, so‐called g‐value, derived from our IPS measurements. We analyzed two ICME events observed in 1997 and 2000. We assumed a shell‐shape ICME model, defined by six parameters (location, propagation directions, radial thickness, angular width, and enhancement factor). We determined the most suitable set of those parameters by matching the model calculations of g‐value to IPS observations. Then, we determined the radial variation of the propagation speed of CME or ICME by comparing our IPS data with coronagraph data and in‐situ data. As result, it is found that the propagation speed of ICME decelerated asV∝r−1.05for the 2000 event andV∝r−0.55the 1997 event. © 2003 American Institute of Physics