Multi-piece solid golf ball

A multi-piece solid golf ball comprising a core, an envelope layer, an intermediate layer and a cover, wherein the core is formed primarily of a base rubber and has a diameter of at least 30 mm;

• the envelope layer and the intermediate layer are each formed of a resin material and the cover is formed primarily of a urethane resin;
• the envelope layer is formed into two layers—an inner layer and an outer layer;
• the core has a center hardness and a surface hardness, the sphere obtained by encasing the core with the inner envelope layer (inner envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer (outer envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere) has a surface hardness and the ball has a surface hardness which together satisfy the following relationship in which the hardnesses are Shore C hardness values:
• core center hardness<core surface hardness<surface hardness of inner envelope layer-encased sphere<surface hardness of outer envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness;
• and the Shore C hardness value obtained by subtracting the core center hardness from the surface hardness of the outer envelope layer-encased sphere is 36 or more, and
• wherein the core is formed of a rubber composition comprising:
• (a) a base rubber,
• (b) a co-crosslinking agent that is an α,β-unsaturated carboxylic acid or a metal salt thereof or both,
• (c) a crosslinking initiator, and
• (d) a lower alcohol having a molecular weight of less than 200.