To provide a method for inoculating spawn in mushroom cultivation, capable of easily and safely doing spawn culture and liquid spawn inoculation through making the best use of the advantage of the liquid spawn inoculation.

This method for inoculating spawn comprises crushing solid medium culture spawn cultured by using an artificial medium having as the main body a solid medium material such as sawdust and corncob, diluting the resultant product in sterile water followed by filtering the resultant diluted solution to obtain spawn and then inoculating a medium for mushroom cultivation with a spawn mixed liquid in which the spawn floats.