According to an aspect of the present invention, there is provided with a screen transmission device, including: a first receiver configured to receive usage state information indicating usage states of a plurality of screen display devices by a user from each the screen display device; a second receiver configured to receive a message of requesting start-up of a window from the screen display device out of the screen display devices; a determiner configured to determine a screen display device on which the window is to be started up out of the plurality of screen display devices based on the usage states of each the screen display device; a screen data generator configured to generate screen data of the window; and a transmitter configured to transmit the screen data of the window to the screen display device determined by the determiner.