FOAMED SHEET

PROBLEM TO BE SOLVED: To provide a foamed sheet having moderate strength without impairing the original flexibility of the foamed sheet.SOLUTION: The foamed sheet is formed by at least laminating a back film 3 sealing opening parts of protrusions 20, on a cap film 2 which is hollowly swollen and where the plurality of the circularly opened protrusions 20 of the same shape are formed in regular arrangement, wherein respective angles of three corners of a triangle OOOformed by connecting centers O, O, O, of three optionally selected adjacent protrusions 20a, 20b, 20c are set to 60±2.5°, and while keeping mutual positional relationship to form an equilateral triangle by the triangle OOO, the respective protrusions 20 are arranged to satisfy a relation of 1.05D≤P≤1.15D between P and D, wherein P is the length of the respective sides of the triangle OOO, and D is an outer diameter of a base part of the protrusions 20.