The present invention provides a multi-piece solid golf ball having 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. The core is formed primarily of a rubber material and has a hardness which gradually increases from a center to a surface thereof, the hardness difference in JIS-C hardness units between the core center and the core surface being at least 15 and, letting (I) be the average value for cross-sectional hardnesses at a position about 15 mm from the core center and at the core center and letting (II) be the cross-sectional hardness at a position about 7.5 mm from the core center, the hardness difference (I)−(II) in JIS-C units being not more than ±2. The envelope layer, intermediate layer and cover have hardnesses which satisfy the condition:
cover hardness>intermediate layer hardness>envelope layer hardness.
The golf ball of the invention has an improved distance, and also has an excellent durability to cracking on repeated impact and an excellent scuff resistance.