PURPOSE: To delay and control release by covering a core of at least one water- soluble agent with a 1st coating having a control capability of a release speed and covering the 1st coating with a 2nd coating having a relatively low water vapor permeation rate.

CONSTITUTION: A water-soluble agent being a mixture of two or three kinds of compounds or over containing elements of N, K, P or the like is formed to be granulates or particles to form a core. An inactive substance such as dried clay or kaolin is added optionally to the core. The core is coated by cyclopentadiene copolymer in a linseed oil to form a 1st coating having a capability of releasing the water-soluble agent at a controlled speed. Then the particles are coated by vinylidene chloride/acrylic ester copolymer or the like in a floating bed coater or the like to form a 2nd coating with a water vapor permeation rate of 2.5 g/m2/day or below. Thus, the product containing plant nutrients is obtained, which is suitable for delayed/controlled release of the water-soluble agent.