An object of the present invention is to provide a positive electrode active substance capable of suppressing gas generation associated with charge and discharge in a lithium secondary battery, and capable of suppressing gas generation associated with charge and discharge particularly even in cases where the use voltage of the lithium secondary battery is high, a positive electrode and a lithium secondary battery using the positive electrode active substance, and methods for producing these. The present invention is a positive electrode active substance for a lithium secondary battery, comprising a coated positive electrode active substance wherein a surface of a positive electrode active substance is directly coated with lithium metaphosphate.