1. A content management system comprising: a content acquisition device that acquires content; and a management device that is communicably connected to the content acquisition device and that manages the content in a searchable manner, wherein the content acquisition device comprises: a first registration unit that registers new content in a search database; and a first search unit that searches content registered in the search database, and wherein the management device comprises: a second registration unit that operates in cooperation with the first registration unit; and a second search unit that operates in cooperation with the first search unit, wherein the first registration unit performs the following operations comprising: (1) transmitting the new content to the management device; (2) receiving a content ID for identifying the new content and a plurality of keyword candidates for searching the new content from the management device; (3) displaying the received keyword candidates; and (4) transmitting a keyword candidate designated from among the displayed keyword candidates and the content ID received by the operation (2) to the management device, wherein the second registration unit performs the following operations comprising: (a) receiving the new content from the content acquisition device; (b) generating the plurality of keyword candidates based on the received new content; (c) associating the received new content with the generated keyword candidates and generating the content ID for identifying the new content; (d) transmitting the content ID and the generated keyword candidates to the content acquisition device; (e) receiving the designated keyword candidate and the content ID from the content acquisition device, and (f) registering the designated keyword candidate as a search keyword in the search database in association with content identified by the content ID received through the operation (e), wherein the first search unit performs the following operations comprising: (5) issuing a search keyword request for searching registered content to the management device; (6) receiving a plurality of search keywords from the management device, (7) transmitting a search keyword designated from among the received search keywords to the management device; (8) receiving content associated with the designated search keyword from the management device, and (9) displaying the received content, and wherein the second search unit performs the following operations comprising: (g) transmitting the search keywords registered in the search database to the content acquisition device in response to the search keyword request from the content acquisition device; (h) extracting content associated with the designated search keyword from the search database; and (i) transmitting the extracted content to the content acquisition device.