A method of forming an injection correction amount map by reading injection correction amount data from an information record medium (62a, 62b, 62c, 62d), and allocating the read injection correction amount data in a map, the method being characterized in that an injection correction amount data array, in which the injection correction amount data are arranged in an order of indexes, is recorded in the information record medium; the injection correction amount map is formed as a two-dimensional array, in which a first index is a fuel pressure value and a second index is an injection period, and correction data for correcting a variation of the fuel injection period for each fuel injection valve (4a, 4b, 4c, 4d) is stored in the injection correction amount map; an allocation map for each kind of the fuel injection valve is formed in accordance with a characteristic of the kind of the fuel injection valve to be employed by changing a number of constituent points of one parameter of the fuel pressure value and the injection period which need allocation of the fuel injection correction amount at each constituent point of another parameter, wherein the allocation map is formed as a two-dimensional array that includes a same number of first indexes as a number of the first indexes in the injection correction amount map and a same number of second indexes as a number of the second indexes in the injection correction amount map, and the indexes in the injection correction amount data array are arranged in the two-dimensional array; variations of the fuel injection periods are measured, forming the injection correction amount data array in which the injection correction amount data obtained based on a result of measurement are arranged in the order of the indexes, and the data array is recorded in the information record medium; and the injection correction amount map is formed by performing, for each of the injection correction amount data recorded in the information record medium, a step of reading the injection correction amount data from the information record medium; a step of computing one or more map positions in the injection correction amount map, into which the read injection correction amount data is to be written, by searching the allocation map for map positions with the index in the injection correction amount data array that corresponds to the read injection correction amount data; and a step of writing the read injection correction amount data into the computed one or more map positions in the injection correction amount map. the method being characterized in that an injection correction amount data array, in which the injection correction amount data are arranged in an order of indexes, is recorded in the information record medium; the injection correction amount map is formed as a two-dimensional array, in which a first index is a fuel pressure value and a second index is an injection period, and correction data for correcting a variation of the fuel injection period for each fuel injection valve (4a, 4b, 4c, 4d) is stored in the injection correction amount map; an allocation map for each kind of the fuel injection valve is formed in accordance with a characteristic of the kind of the fuel injection valve to be employed by changing a number of constituent points of one parameter of the fuel pressure value and the injection period which need allocation of the fuel injection correction amount at each constituent point of another parameter, wherein the allocation map is formed as a two-dimensional array that includes a same number of first indexes as a number of the first indexes in the injection correction amount map and a same number of second indexes as a number of the second indexes in the injection correction amount map, and the indexes in the injection correction amount data array are arranged in the two-dimensional array; variations of the fuel injection periods are measured, forming the injection correction amount data array in which the injection correction amount data obtained based on a result of measurement are arranged in the order of the indexes, and the data array is recorded in the information record medium; and the injection correction amount map is formed by performing, for each of the injection correction amount data recorded in the information record medium, a step of reading the injection correction amount data from the information record medium; a step of computing one or more map positions in the injection correction amount map, into which the read injection correction amount data is to be written, by searching the allocation map for map positions with the index in the injection correction amount data array that corresponds to the read injection correction amount data; and a step of writing the read injection correction amount data into the computed one or more map positions in the injection correction amount map. a step of reading the injection correction amount data from the information record medium; a step of computing one or more map positions in the injection correction amount map, into which the read injection correction amount data is to be written, by searching the allocation map for map positions with the index in the injection correction amount data array that corresponds to the read injection correction amount data; and a step of writing the read injection correction amount data into the computed one or more map positions in the injection correction amount map.