Immersion nozzle for continuous casting

An immersion nozzle for continuous casting, comprising:

• a flow passage;
• an opening;
• a first portion;
• a connecting portion;
• and
• a second portion,
• the first portion, the connecting portion, and the second portion being arranged in this order from a proximal end side of the immersion nozzle, wherein
• a cross-sectional shape of the flow passage is circular in the first portion,
• a cross-sectional shape of the flow passage in the second portion is a shape having a length in a long-side direction 1.5 times or more a length in a short-side direction;
• in the connecting portion, a shape of the flow passage is a shape continuously connecting the flow passage of the first portion and the flow passage of the second portion,
• the opening is in a portion of the second portion proximate to a distal end, and
• a maximum value of a cross-sectional area of the flow passage in the first portion is S1, a maximum value of a cross-sectional area of the flow passage in the second portion is S2, and a minimum value of a cross-sectional area of the flow passage within a range of 20% of a length of the first portion from a boundary portion between the first portion and the connecting portion toward an upstream side is S3,
• S2 is greater than S1,
• a ratio S1/S3 between S1 and S3 is 1.10 or more and 2.00 or less,
• a ratio S2/S3 between S2 and S3 is 1.20 or more and 2.50 or less,
• a ratio of a length of the second portion to the total length is 8% or more and 50% or less, and
• a ratio of a length of the connecting portion to the total length is 8% or more and 50% or less.