A threaded connection for steel pipe comprising a tubular pin and a tubular box, the pin and the box being made up as the pin is screwed into the box, wherein: the pin includes, in order from a tip of the pin toward a base of the pin: a first male-threaded section; an intermediate seal section; and a second male-threaded section, the pin further includes an intermediate shoulder surface provided between the first male-threaded section and the intermediate seal section of the pin to face the tip; the box includes, in order from an interior of the box onward: a first female-threaded section adapted such that the first male-threaded section of the pin is fitted therein when the connection is made up; an intermediate seal section adapted such that the intermediate seal section of the pin is fitted thereto when the connection is made up; and a second female-threaded section adapted such that the second male-threaded section of the pin is fitted therein when the connection is made up, the box further includes an intermediate shoulder surface provided between the first female-threaded section and the intermediate seal section of the box, the intermediate shoulder surface of the box facing the intermediate shoulder surface of the pin, these shoulder surfaces facing in an axial direction of the threaded connection; the pin has a pin intermediate critical cross section (PICCS) located near an end of the first male-threaded section that is located closer to a base; and the box has a box critical cross section (BCCS) located near an end of the first female-threaded section that is located further toward the interior; and a box intermediate critical cross section (BICCS) located near an end of the second female-threaded section that is located further toward the interior; characterized in that the pin and the box satisfy the following relationships: PICCSA + BICCSA > BCCSA, and 0.70 ≤ PICCSA/BICCSA ≤ 0.95, where PICCSA is the area of the pin intermediate critical cross section (PICCS) found when the pin and the box are not made up, BICCSA is the area of the box intermediate critical cross section (BICCS) found when the pin and the box are not made up, and BCCSA is the area of the box critical cross section (BCCS) found when the pin and the box are not made up. the pin includes, in order from a tip of the pin toward a base of the pin: a first male-threaded section; an intermediate seal section; and a second male-threaded section, the pin further includes an intermediate shoulder surface provided between the first male-threaded section and the intermediate seal section of the pin to face the tip; the box includes, in order from an interior of the box onward: a first female-threaded section adapted such that the first male-threaded section of the pin is fitted therein when the connection is made up; an intermediate seal section adapted such that the intermediate seal section of the pin is fitted thereto when the connection is made up; and a second female-threaded section adapted such that the second male-threaded section of the pin is fitted therein when the connection is made up, the box further includes an intermediate shoulder surface provided between the first female-threaded section and the intermediate seal section of the box, the intermediate shoulder surface of the box facing the intermediate shoulder surface of the pin, these shoulder surfaces facing in an axial direction of the threaded connection; the pin has a pin intermediate critical cross section (PICCS) located near an end of the first male-threaded section that is located closer to a base; and the box has a box critical cross section (BCCS) located near an end of the first female-threaded section that is located further toward the interior; and a box intermediate critical cross section (BICCS) located near an end of the second female-threaded section that is located further toward the interior; characterized in that the pin and the box satisfy the following relationships: PICCSA + BICCSA > BCCSA, and 0.70 ≤ PICCSA/BICCSA ≤ 0.95, where PICCSA is the area of the pin intermediate critical cross section (PICCS) found when the pin and the box are not made up, BICCSA is the area of the box intermediate critical cross section (BICCS) found when the pin and the box are not made up, and BCCSA is the area of the box critical cross section (BCCS) found when the pin and the box are not made up.