Shoe sole including laminate-structured midsole

A shoe sole comprising:

• an outsole having a tread surface;
• and a midsole arranged on the outsole, wherein:
• the midsole includes an upper layer and a lower layer each of a foamed material;
• the upper layer is a low-hardness foamed material having a thermoplastic resin component;
• the lower layer is a high-hardness foamed material that has a thermoplastic resin component and has a high hardness that is higher than a hardness of the low-hardness foamed material;
• the upper layer is seamlessly and integrally continuous from a posterior end portion of a rear foot portion to an anterior end portion of a forefoot portion;
• the lower layer is seamlessly and integrally continuous from the posterior end portion of the rear foot portion to a posterior end portion of the forefoot portion;
• a boundary line, which is a line of an anterior end of the lower layer and is an anterior-posterior boundary between the upper layer and the lower layer, is arranged at the posterior end portion of the forefoot portion;
• in the forefoot portion, a lower surface of the upper layer includes a primary tread portion between a medial edge portion and a lateral edge portion of the midsole, and a line of a posterior end of the primary tread portion is defined by the boundary line;
• in the primary tread portion of the forefoot portion anterior to the boundary line, an upper surface of the outsole is attached to the lower surface of the upper layer;
• and
• the low-hardness foamed material of the upper layer is made from a low-hardness, high-resilience material having a higher specific gravity than the high-hardness foamed material,
• the low-hardness, high-resilience material having a low hardness that is lower than the hardness of the high-hardness foamed material, and
• the low-hardness, high-resilience material having a higher speed at which to recover to an original shape after being deformed than that of the high-hardness foamed material.