Dental handpiece having cleaning unit

A dental handpiece having a cleaning unit comprising a turbine gas supply passage for supplying a gas under pressure to a turbine for rotationally driving a dental tool, a rinsing liquid supply passage for supplying a rinsing liquid to a turbine head, a chip-scattering gas supply passage for supplying a gas for scattering cut chips produced by operation of said dental tool, cleaning means for cleaning at least one of the gas and the liquid provided in at least one of said turbine gas supply passage, said rinsing liquid supply passage and said chip-scattering gas supply passage, and a gas exhaust passage for discharging the gas under pressure to outside after having run the turbine in rotation, said cleaning means being provided in said gas exhaust passage, said cleaning means comprising a filter and a transparent member for securing said filter.