An ink supply device of a printing machine, said ink supply device comprising a plurality of ink transfer rollers, an ink fountain roller which constitutes an ink fountain and a control device, wherein the plurality of ink transfer rollers are divided in the lengthwise direction of the ink fountain roller which constitutes the ink fountain are arranged adjacent to the ink fountain roller, the respective ink transfer rollers are individually changeable over between a transfer position where the ink transfer roller is brought into contact with the ink fountain roller and a non-transfer position where the ink transfer roller is disposed away from the ink fountain roller, and using the control device, based on a graph value set corresponding to a pattern area of a printed matter, ink is transferred by changing over a position of a required ink transfer roller for every transfer timing at predetermined intervals, and a rotational angle of the ink fountain roller from a position where the ink transfer roller is brought into contact with the ink fountain roller to a position where the ink transfer roller is separated from the ink fountain roller is controlled for every ink transfer roller thus controlling a circumferential length of ink transferred to the ink transfer roller from the ink fountain roller, wherein the graph value is a target value of an ink quantity indicating a quantity of ink having predetermined color to be used for every ink transfer roller, each ink transfer roller is provided with a roller position switching device which is able to change over the position of the ink transfer roller, each switching device is controllable by the control device, characterized in that the control device comprises: a concentration prediction value calculation means which acquires a concentration prediction value when the concentration of ink becomes stable based on concentration of ink measured values of a predetermined number of printed matters; a graph change value calculation means which acquires a graph change value using the concentration prediction value and a concentration target value; and a control graph value calculation means which acquires a control graph value for controlling the rotational angle of the required ink fountain roller based on a preset set graph value and the graph change value, wherein a graph value before a change is Gb and a changed graph value is Ga, wherein a graph change value resulting from Ga-Gb is Gs and the quantity of ink to be supplied by 1 circumference of the ink transfer roller is Gm; wherein at the time of changing the graph value to Ga from Gb, Gs=Ga-Gb, the graph value is temporarily set to Gz1, and after a graph change value amounting to predetermined temporary number of cycles, i.e. circumferences of the ink transfer roller, is outputted, the temporary graph value Gz1 is outputted, and the temporary graph value Gz1 amounting to 1 cycle is acquired by Gz1=Ga+{(γ×Gs)/ε}, wherein γ and ε are concentration correction coefficients of natural numbers, wherein 1) when the graph value Gz1 is a positive value and is smaller than a graph change value amounting to 1 circumference of the ink transfer roller, the graph change value Gz1 is acquired by Gz1=Ga+{(γ×Gs)/ε} during a period that the temporary number of cycles S is ε (S=ε), or 2) when the graph value Gz1 exceeds the graph change value amounting to 1 circumference of the ink transfer roller, the graph change value Gz1 is set to Gm, Gz1=Gm, during a period that the temporary number of cycles S is expressed by S=(γ×Gs)/(Gm-Ga), or 3) when the temporary graph value Gz1 amounting to 1 cycle is 0 or a negative value, the graph change value Gz1 is set to 0%, Gz1=0%, during a period where the temporary number of cycles S is expressed by S=(γ×Gs)/Ga. the graph value is a target value of an ink quantity indicating a quantity of ink having predetermined color to be used for every ink transfer roller, each ink transfer roller is provided with a roller position switching device which is able to change over the position of the ink transfer roller, each switching device is controllable by the control device, characterized in that the control device comprises: a concentration prediction value calculation means which acquires a concentration prediction value when the concentration of ink becomes stable based on concentration of ink measured values of a predetermined number of printed matters; a graph change value calculation means which acquires a graph change value using the concentration prediction value and a concentration target value; and a control graph value calculation means which acquires a control graph value for controlling the rotational angle of the required ink fountain roller based on a preset set graph value and the graph change value, 1) when the graph value Gz1 is a positive value and is smaller than a graph change value amounting to 1 circumference of the ink transfer roller, the graph change value Gz1 is acquired by Gz1=Ga+{(γ×Gs)/ε} during a period that the temporary number of cycles S is ε (S=ε), or 2) when the graph value Gz1 exceeds the graph change value amounting to 1 circumference of the ink transfer roller, the graph change value Gz1 is set to Gm, Gz1=Gm, during a period that the temporary number of cycles S is expressed by S=(γ×Gs)/(Gm-Ga), or 3) when the temporary graph value Gz1 amounting to 1 cycle is 0 or a negative value, the graph change value Gz1 is set to 0%, Gz1=0%, during a period where the temporary number of cycles S is expressed by S=(γ×Gs)/Ga.