This report is the result of devising a method for utilizing the device of the load cell to maintain a constant watercontent of the medium every day to prepare a cultural substrates with the mixer for growing mushrooms bottle cultivation. A loadcell was device under the medium mixer. It is developed when the device reaches the weight calculated as amount of substratebottled and number of the bottle, it is automatically terminated by water injection. In addition, measuring the water content ofeach medium and the total weight of the medium reaches the target moisture content were calculated by using the programCheong et al. (2015). Enter the total weight of the medium on the display unit of the load cell, when starting the water supply toreach the weight-based mixing media, the water supply is stopped. This method can improve the convenience by reducing theuser's trouble in repeated work medium prepared by automating water supply. The suitable moisture content of the mixedmedium for some kind of mushroom can be improved by the composition accuracy. And mycelial culture period, primordialperiod, mushroom growing period is maintained even of the medium can be produced stably. Therefore, it is possible to achievea stable management of the mushroom farm according to mushroom quality and quantity stable throughout the year.