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Radio emission from supernovae (SNe) is believed to attribute to synchrotron emission from electrons accelerated by an SN shock propagating circumstellar medium (CSM). Since the lengthscale and density of CSM reflect the lookback timescale and the magnitude of mass-loss activities of SN progenitors, respectively, radio emission can be used as an indicator of the stellar evolution of massive stars in the viewpoint of mass-loss activities. Recent transient survey facilities and rapid optical follow-up observations have indicated that at least a fraction of SN progenitors experiences enhanced mass-loss activities just prior to the explosion. Here we suggest millimeter emission (~100GHz) from SNe immediately after the shock breakout as an independent tracer of the nature of the circumstellar environment in the vicinity of SN progenitors. This enables us to examine the final moment of massive stars prior to the core collapse, highlighting the importance of target of opportunity observations by Atacama Large Millimeter/submillimeter Array. In this talk we introduce our recent works related to the modeling of radio emission from infant SNe, including future prospects and application of our method to the examination of properties of supernova remnants.