A steel sheet, wherein a chemical composition consists of, by mass%: C: more than 0.25% and 0.48% or less; Si: 0.10% to 0.60%; Mn: 0.40% to 0.90%; Al: 0.003% to 0.070%; Ca: 0.0005% to 0.0040%; REM: 0.0003% to 0.0050%; Cu: 0% to 0.05%; Nb: 0% to 0.05%; V: 0% to 0.05%; Mo: 0% to 0.05%; Ni: 0% to 0.05%; Cr: 0% to 0.50%; B: 0% to 0.0050%; P: limited to 0.020% or less; S: 0.0003% to 0.0070%; Ti: limited to 0.050% or less; O: limited to 0.0040% or less; N: limited to 0.0075% or less; and remainder of iron and impurity, amounts of each elements by mass% in the chemical composition satisfy both of expression 1 and expression 2, a number density of carbonitrides including Ti which exists independently and has a long side of 5 μm or more is limited to 5 pieces/mm 2 or less, 0.3000 ≤ Ca / 40.88 + REM / 140 / 2 S / 32.07 ≤ 5.000 0.0005 ≤ Ca ≤ 0.0058 − 0.0050 × C a number density of A-type inclusions, which are defined as inclusions of which an aspect ratio is 3.0 or more, is 6 pieces/mm 2 or less, a total number density of B-type inclusions, which are defined as inclusions which form inclusion groups in which three or more of the inclusions form a line along to the working direction, in which clearance between the inclusions is 50 μm or less, and in which the aspect ratio of the inclusions is less than 3.0, and C-type inclusions, which are defined as inclusions of which an aspect ratio is 3.0 or less, and which disperse in a random manner, is 6 pieces/mm 2 or less, a number density of coarse inclusions, which are defined as inclusions which are B-type or C-type and of which maximum length is 20 μm or more, is 6 pieces/mm 2 or less, and the steel sheet further includes a composite inclusion which includes Al, Ca, O, S, and REM. C: more than 0.25% and 0.48% or less; Si: 0.10% to 0.60%; Mn: 0.40% to 0.90%; Al: 0.003% to 0.070%; Ca: 0.0005% to 0.0040%; REM: 0.0003% to 0.0050%; Cu: 0% to 0.05%; Nb: 0% to 0.05%; V: 0% to 0.05%; Mo: 0% to 0.05%; Ni: 0% to 0.05%; Cr: 0% to 0.50%; B: 0% to 0.0050%; P: limited to 0.020% or less; S: 0.0003% to 0.0070%; Ti: limited to 0.050% or less; O: limited to 0.0040% or less; N: limited to 0.0075% or less; and remainder of iron and impurity, amounts of each elements by mass% in the chemical composition satisfy both of expression 1 and expression 2, a number density of carbonitrides including Ti which exists independently and has a long side of 5 μm or more is limited to 5 pieces/mm 2 or less, 0.3000 ≤ Ca / 40.88 + REM / 140 / 2 S / 32.07 ≤ 5.000 0.0005 ≤ Ca ≤ 0.0058 − 0.0050 × C a number density of A-type inclusions, which are defined as inclusions of which an aspect ratio is 3.0 or more, is 6 pieces/mm 2 or less, a total number density of B-type inclusions, which are defined as inclusions which form inclusion groups in which three or more of the inclusions form a line along to the working direction, in which clearance between the inclusions is 50 μm or less, and in which the aspect ratio of the inclusions is less than 3.0, and C-type inclusions, which are defined as inclusions of which an aspect ratio is 3.0 or less, and which disperse in a random manner, is 6 pieces/mm 2 or less, a number density of coarse inclusions, which are defined as inclusions which are B-type or C-type and of which maximum length is 20 μm or more, is 6 pieces/mm 2 or less, and the steel sheet further includes a composite inclusion which includes Al, Ca, O, S, and REM.