The invention provides a steam valve and a steam turbine, wherein the steam valve (1) equipped with: a stop valve (2) capable of stopping/releasing the flow of steam when driven so as to open/close; an adjustment valve (3) that is provided coaxially in the interior of the stop valve (2), and that controls the flow volume of the steam when driven to open/close in the same direction as the opening/closing of the stop valve (2); and a first guide part (11) that is provided between the stop valve (2) and the adjustment valve (3) so as to separate the stop valve and the adjustment in the radial direction, and that guides at least the adjustment valve in the opening/closing direction.