  We suggest "tidal double detonation": a new mechanism for a thermonuclear
explosion of a white dwarf (WD) induced by a tidal disruption event (TDE).
Tidal detonation is also a WD explosion induced by a TDE. In this case, helium
(He) and carbon-oxygen (CO) detonation waves incinerate He~WD and CO~WD,
respectively. On the other hand, for tidal double detonation, He detonation is
first excited in the He shell of a CO~WD, and drives CO detonation in the CO
core. We name this mechanism after the double detonation scenario in the
context of type Ia supernovae. In this paper, we show tidal double detonation
occurs in shallower encounter of a CO~WD with an intermediate mass black hole
(IMBH) than simple tidal detonation, performing numerical simulations for
CO~WDs with $0.60M_\odot$ with and without a He shell. We expect tidal double
detonation spreads opportunity to WD~TDEs illuminating IMBHs.
