Multi-piece solid golf ball

A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover which encases the intermediate layer and has formed on a surface thereof a plurality of dimples,

• wherein the core is formed primarily of one or more thermoplastic elastomer selected from the group consisting of polyester, polyamide, polyurethane, olefin and styrene-type thermoplastic elastomers and has a diameter of from 10 to 30 mm, a specific gravity of more than 1.0 and less than 1.3, and a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) of from 3.6 to 10 mm,
• the envelope layer is formed of a rubber composition containing primarily a rubber material and has a thickness of from 3 to 10 mm,
• the intermediate layer is formed of a resin composition containing primarily an ionomer, and the cover is formed of a resin composition containing primarily a urethane;
• wherein the intermediate layer has a specific gravity of less than 1.0;
• wherein the envelope layer, the intermediate layer and the cover have specific gravities which satisfy the condition:
• envelope layer specific gravity>intermediate layer specific gravity<cover specific gravity;
• and wherein the core, the envelope layer, the intermediate layer and the cover have Shore D surface hardnesses which satisfy the condition:
• core surface hardness<envelope layer surface hardness<intermediate layer surface hardness>cover surface hardness.