Energy　dissipators　are　being　increasingly　utilized　in　the　seismic　protection　of　both　newly　constructed　and　ret-rofitted　buildings.　However,　their　control　effectiveness　would　decline　when　applied　to　the　stiff　structures　with　small　responses,　such　as　drifts　and　inter-story　velocities.　To　more　effectively　dissipate　the　vibration　energy,　this　paper　proposes　a　novel　energy　dissipator　dubbed　as　tuned　torsional　mass　damper　(TTMD)　based　on　the　ampli-fication　effect　of　inerter.　In　particular,　the　conceptual　design　and　ideal　mechanical　model　of　the　proposed　TTMD　are　firstly　elaborated.　A　single　degree　of　freedom　(SDOF)　system　is　then　established　to　derive　the　optimal　pa-rameters　of　TTMD,　namely　the　frequency　and　damping　ratios,　based　on　the　fixed-point　theory.　Subsequently,　a　three-story　benchmark　building　is　adopted　to　demonstrate　the　control　effectiveness　of　TTMD　in　the　frequency　domain.　For　comparison,　the　control　effectiveness　of　the　conventional　viscous　damper　(VD)　and　viscous　mass　damper　(VMD)　are　also　examined.　Moreover,　parametric　studies　are　conducted　to　investigate　the　influences　of　the　mass　ratio,　secondary　mass　ratio,　and　lead　of　ball　screw　on　the　control　performances　of　TTMD,　and　sensitivity　analyses　are　also　performed　to　assess　the　robustness　of　TTMD　against　the　structural　uncertainties.　Finally,　case　studies　are　performed　to　further　illustrate　the　control　performance　and　the　hysteretic　behaviors　of　TTMD　in　the　time　domain.　The　results　show　that　the　proposed　TTMD　is　more　effective　than　the　conventional　VD　and　VMD　in　reducing　the　seismic　responses　of　building;　the　relative　angle　of　TTMD　can　be　effectively　reduced　by　increasing　either　the　mass　ratio　or　the　lead　of　ball　screw.　The　proposed　TTMD　could　be　a　promising　and　viable　alternative　to　conventional　dampers　in　the　field　of　structural　vibration　control.