A gradual releasing capsule having large mechanical strength, a large grain size and excellent gradual-releasability and its production method are disclosed. The capsule comprises a polymer core body containing a hydrophobic oil and a shell body formed of a cured body with which the surface of the core body is covered. The capsule is produced by dripping a core body-forming composition containing a hydrophobic oil and a reactive monomer and a curable polymer-containing solution from a multiple nozzle into a coagulating solution to form a primary capsule and then polymerizing the reactive monomer in the primary capsule.