A network system includes a first communication device, a second communication device and a keyword database. The first communication device includes a first input device and a first search device. The first input device allows a user to input a keyword. The first search device is capable of carrying out a first search process that includes sending the keyword input to the first input device to a search engine and receiving a search result. The keyword database stores the keyword used for the first search process. The second communication device is composed separately from the first communication device. The second communication device includes a keyword acquisition device and a second search device. The keyword acquisition device is capable of acquiring the keyword from the keyword database. The second search device is capable of carrying out a second search process that includes sending the keyword acquired by the keyword acquisition device to a search engine and receiving a search result.