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The isotope $^{220}\mathrm{Pa}$ produced in the reaction $^{40}\mathrm{Ar}+^{187}\mathrm{Re}$ at a beam energy of 198.7 MeV was reinvestigated via the $\ensuremath{\alpha}$-spectroscopic method. A new $\ensuremath{\alpha}$-decaying state in $^{220}\mathrm{Pa}$ has been observed with an energy ${E}_{\ensuremath{\alpha}}=9664(40)\phantom{\rule{0.28em}{0ex}}\mathrm{keV}$ and with a half-life ${T}_{1/2}={233}_{\ensuremath{-}56}^{+108}\phantom{\rule{0.28em}{0ex}}\mathrm{ns}$. The spin parity of the state is tentatively suggested to be (${3}^{\ensuremath{-}}$). The $\ensuremath{\alpha}$ energy and half-life of the (${1}^{\ensuremath{-}}$) ground state are measured to be ${E}_{\ensuremath{\alpha}}=9548(30)\phantom{\rule{0.28em}{0ex}}\mathrm{keV}$ and ${T}_{1/2}=0.75(8)\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{s}$, respectively. The reduced $\ensuremath{\alpha}$ width, inferred from the present data, fits well into the systematics for $N=129$ isotones.