Synchrotron radiation from Jupiter at λ20 cm (1420 MHz) and λ74 cm (408 MHz) was monitored using the DRAO synthesis radio telescope during the infall of the cometary fragments of Shoemaker-Levy 9 (Comet l993e) between 1994 July 16 and July 22. Follow-up observations were also conducted later in 1994 August and September. Although no abrupt changes were detected in the integrated flux density of Jupiter during the impact period, slow enhancements of ≍1 Jy over a time scale of few days were observed at both wavelengths Subsequently, a steady decline in Jupiter's integrated flux density has been observed at λ20, while the decline at λ74 is more rapid and the flux density has even dropped below the preimpact level during 1994 September. These observations imply significant changes to the Jovian magnetosphere during and after the impact of the cometary fragments. Models suggesting energy-dependent energization of relativistic electrons as well as hardening of the electron energy spectrum by cometary dust in Jupiter's magnetosphere are found to be broadly consistent with the radio observations.