An information retrieval apparatus includes an acquiring unit that acquires a numerical value defining a boundary of a numerical range; a detecting unit that detects a number of places in and a head numeral of the numerical value; an extracting unit that extracts from a bit string group, a bit string indicating whether a numerical value in a numerical value group having the number of places and the head numeral is present in files subject to retrieval; a specifying unit that specifies a file corresponding to a bit in the extracted bit string, the bit indicating the presence of a numerical value of the numerical value group; a determining unit that determines whether a numerical value in the specified file meets the boundary condition; and a designating unit that, based on a determination by the determining unit designates the specified file to have a numerical value within the numerical range.