1. A data retrieval device, comprising: a storage part that stores data; a retrieval item divider that divides retrieval conditions related to a predetermined retrieval item into a plurality of retrieval condition classes; a retrieval part that respectively sorts the data stored in the storage part into the plurality of retrieval condition classes formed by the retrieval item divider by searching for data that respectively satisfies the retrieval conditions corresponding to each retrieval condition class; an output part that respectively associates the plurality of retrieval condition classes with information related to the data sorted into the retrieval condition classes by the retrieval part, and outputs the same; an input part that receives commands input from a user; a class unit modifier that further divides a selected retrieval condition class into a plurality of retrieval condition classes when a command selecting one of the retrieval condition classes from among the plurality of retrieval condition classes output by the output part is input into the input part; and a retrieval controller that controls the retrieval part to respectively sort the data that was sorted into the retrieval condition class selected by the input part into the retrieval condition classes formed by the class unit modifier; wherein the output part includes a display part that partitions a retrieval screen into a matrix structure, respectively associates regions of matrix positions in the matrix structure with the plurality of retrieval condition classes, and displays information related to the data sorted into each retrieval condition class in the corresponding region; wherein the retrieval conditions comprise combinations of a plurality of first retrieval conditions, which are formed by dividing a row retrieval item belonging to the predetermined retrieval item into predetermined class units which are set as rows of the matrix structure, and a plurality of second retrieval conditions, which are formed by dividing a column retrieval item belonging to the predetermined retrieval item into predetermined class units which are set as columns of the matrix structure; wherein the retrieval part respectively associates the retrieval condition classes with the matrix positions, and respectively sorts data that satisfies the retrieval conditions corresponding to a particular matrix position into that particular matrix position; wherein the display part displays retrieval results information, which indicates the retrieval results of the retrieval part, in the respective matrix positions, the retrieval results information respectively corresponding to the data sorted by the retrieval part into the respective matrix positions; wherein the class unit modifier modifies the class units dividing the row retrieval item and the class units dividing the column retrieval item for a selected matrix position when a command to modify the class units and a command selecting a single matrix position from among the matrix positions displayed by the display part is input into the input part; wherein the retrieval controller respectively associates retrieval conditions with matrix positions and causes the retrieval part to sort data, the retrieval conditions being combinations of the plurality of first retrieval conditions and the plurality of second retrieval conditions divided by the class units that were modified by the class unit modifier, and the data being the data that was sorted into the matrix position selected via the input part; wherein the data retrieval device further comprises a class unit modification controller that controls the class unit modifier to modify the class units dividing the row retrieval item and the class units dividing the column retrieval item when a command to modify the class units is input a predetermined number of times into the input part, and additionally, enlarges the retrieval screen displayed by the display part every time the command to modify the class units is input until the command is input the predetermined number of times into the input part; and wherein when the command to modify the class units is input the predetermined number of times so as to perform class modification, the retrieval screen is modified in accordance with the class modification such that the rows and columns of the matrix structure are respectively set to correspond only to the modified class units, and not to the respective class units previously set as the rows and columns of the matrix structure before the class modification was performed.