A multifuel internal combustion engine includes: fuel characteristics determining unit that determines ignitability and anti-knocking performance of the fuel introduced into the combustion chamber CC; combustion mode setting unit that sets a compression hypergolic diffusion combustion mode when ignitability of the fuel is excellent, sets a premixed spark-ignition flame propagation combustion mode when the ignitability of the fuel is poor and anti-knocking performance is excellent, and sets a spark assist compression hypergolic diffusion combustion mode when both the ignitability and anti-knocking performance of the fuel are poor; and combustion control execution unit that makes the engine to drive in a combustion mode which is set by the combustion mode setting unit.