To provide an ethylene-based polymer and a resin composition for foaming blow molding having specific physical properties which has a high expansion ratio, can be reduced in weight and is excellent in heat insulating properties and reduced in wall thickness deviation.

There is provided a resin composition for foaming blow molding which contains (A) 10 to 99 wt.% of an ethylene-based polymer produced from a metallocene catalyst satisfying the physical properties (a)to (d) and (B) 1 to 90 wt.% of an ethylene-based polymer produced from a Ziegler catalyst satisfying the physical properties (e) to (i). (a): an MFR of 1.0/10 min or more and less than 10 g/10 min, (b): a density of 935 kg/m³ or more, (c): an Mw/Mn of 6.0 to 15, (d): a melt tension of 11.5 to 40 cN, (e) an MFR of 0.01 g/10 min or more and less than 1 g/10 min, (f): a density of 935 kg/m³ or more, (g): an Mw/Mn of 6.0 to 30, (h): a melt tension of 2.0 to 40 cN, (i): an MFR of 0.05 g/10 min or more and less than 1.0 g/10 min.