<p>A double seat valve formed in a simple structure, capable of accurately and stably performing flow control, and enabling a reduction in size, comprising one flow passage formed of a lateral joint (15) -> a lateral hole (27) -> an intermediate chamber (26) -> a first valve port (21) -> a lower joint (16) and the other flow passage formed of the lateral joint (15) -> the lateral hole (27) -> the intermediate chamber (26) -> a second valve port (22) -> an end chamber (25) -> an internal passage (34) -> the lower joint (16).</p>
