Threshold photoelectron-photoion coincidence (TPEPICO) spectra of ArKr were measured between the ionization threshold and 16.0 eV by using the penetrating field technique and synchrotron radiation. The ground state (X 1/2 state) vibrational progression of ArKr+ was observed from nu＇=2 to 27 and the first ionization energy was estimated to be 108 703+/-12 cm(-1) by extrapolation to nu＇=0. The other excited states constructed from the ground state atom and ion were also observed. The ionization energies to the A(1) 3/2, A(2) 1/2, C-1 3/2, B 1/2, and C-2 1/2 states from the neutral ground state were 112274, 117388, 126211, 126614, and 127952 cm(-1),respectively.