A misfire detection system for an internal combustion engine, the misfire detection system comprising: a crank angle sensor configured to detect a rotation angle position of a crankshaft of the internal combustion engine; a misfire detection unit configured to detect a misfire condition in the internal combustion engine based on a misfire index, the misfire index being derived from a rotation speed of the crankshaft as a reference corresponded to a predetermined order of engine speed of an output signal from the crank angle sensor, and having a correlation with an amount of variation in an angular velocity of the crankshaft such that a value of the misfire index varies in accordance with the amount of variation in the angular velocity of the crankshaft; an acquisition unit configured to obtain a parameter relating to a compression end pressure (Ptdc) in a cylinder of the internal combustion engine; and a correction unit configured to correct the misfire index, or a predetermined misfire detection parameter used together with the misfire index during misfire detection by the misfire detection unit, based on the parameter obtained by the acquisition unit, the misfire detection system being characterized in that, the predetermined misfire detection parameter is a predetermined threshold relating to the misfire index, which is used by the misfire detection unit to determine whether or not a misfire has occurred, the misfire detection unit is configured to detect the misfire when the misfire index is larger than the predetermined threshold, and the correction unit is configured to correct the misfire index such that when the value of the parameter obtained by the acquisition unit is converted into the compression end pressure (Ptdc) in the cylinder, a correction amount applied to the misfire index or the predetermined threshold increases as a resulting converted value increases. a crank angle sensor configured to detect a rotation angle position of a crankshaft of the internal combustion engine; a misfire detection unit configured to detect a misfire condition in the internal combustion engine based on a misfire index, the misfire index being derived from a rotation speed of the crankshaft as a reference corresponded to a predetermined order of engine speed of an output signal from the crank angle sensor, and having a correlation with an amount of variation in an angular velocity of the crankshaft such that a value of the misfire index varies in accordance with the amount of variation in the angular velocity of the crankshaft; an acquisition unit configured to obtain a parameter relating to a compression end pressure (Ptdc) in a cylinder of the internal combustion engine; and a correction unit configured to correct the misfire index, or a predetermined misfire detection parameter used together with the misfire index during misfire detection by the misfire detection unit, based on the parameter obtained by the acquisition unit, the misfire detection system being characterized in that, the predetermined misfire detection parameter is a predetermined threshold relating to the misfire index, which is used by the misfire detection unit to determine whether or not a misfire has occurred, the misfire detection unit is configured to detect the misfire when the misfire index is larger than the predetermined threshold, and the correction unit is configured to correct the misfire index such that when the value of the parameter obtained by the acquisition unit is converted into the compression end pressure (Ptdc) in the cylinder, a correction amount applied to the misfire index or the predetermined threshold increases as a resulting converted value increases.