1. A bio-item searching apparatus that searches for a target bio-item with a keyword input by a user, comprising a processor, a storage device, and an output device, wherein the storage device includes: a bio-item literature set storage unit that stores one or more bio-item literature sets having a literature in which a bio-item name is described for each of a plurality of bio-items, and an all-literature set storage unit that stores an all-literature set having all literatures included in each of the bio-item literature sets, and the control processor includes: a number-of-literatures acquiring unit that searches each of the bio-item literature sets with the keyword to acquire a number-of-literatures, Nh, including the keyword for each of the bio-items, and searches the all-literature set with the keyword to acquire a number-of-literatures including the keyword, Nk; a candidate bio-item selecting unit that selects the bio-items in which the number-of-literatures Nh is 1 or larger as candidate bio-items; a table creating unit that creates, for each of the candidate bio-items, a number-of-literatures table constituted by a) the number-of-literatures Nh, b) a number-of-literatures each not including the keyword and including the bio-item name, the number-of-literatures in the bio-item literature set of the bio-item minus Nh; c) a number-of-literatures each including the keyword and not including the bio-item name, Nk−Nh, and d) a number-of-literatures each not including the keyword and not including the bio-item, the total number-of-literatures in the all-literature set minus the number-of-literatures in the bio-item literature set minus Nk+Nh; a correlation score calculating unit that calculates a correlation score between the bio-item and the keyword based on a statistical calculation by using the number-of-literatures table for each of the candidate bio-items; and an output unit that outputs the candidate bio-items to the output device based on the correlation score calculated by the correlation score calculating unit.