The present invention relates to an automatic negative pressure generating device comprising: a cupping container directly placed on the skin of a user and a negative pressure generating unit for generating negative pressure by making the inside of the cupping container into a vacuum state. In particular, the automatic negative pressure generating device comprises: a negative pressure selecting unit for enabling a user to select an optional negative pressure generation mode among selection modes verified into a weak mode, an intermediate mode, and a strong mode on the basis of the degree of negative pressure a solenoid valve for connecting or blocking an exhaust pipe connected between the cupping container and the negative pressure generating unit by means of an operation control signal and a negative pressure detecting unit for detecting whether a particular level of negative pressure is generated in the cupping octnainer by the negative pressure generating unit and a negative pressure maintaining unit for blocking the exhaust pipe connected between the cupping container and the negative pressure generating unit by delaying time corresponding to a mode selected by the negative pressure selecting unit and by transferring a control signal for an ON operation signal to a solenoid valve side when it is determined that a particular level of negative pressure is generated in the negative pressure detecting unit, and connecting the exhaust pipe connected with the cupping container and the negative pressure generating unit by delaying time corresponding to a mode selected by the negative pressure selecting unit and by transferring a control signal for an OFF operation signal to a solenoid valve side when it is determined that a particular level of negative pressure is not generated in the negative pressure detecting unit. Negative pressure is not regularly generated, but is generated on the basis of the selection of a user according to selection modes (weak, intermediate,
