(Currently Amended) A hand-operated pump comprising: a button having a discharge hole; a housing constituting the external appearance of a plump; a cloture coupled with the outer surface in the upper portion of the housing through a housing cap to mount the housing in a container; a stem having a horizontal passage communicated with the inner space of the housing and a vertical passage communicated with the horizontal passage and vertically moved while protruding from the upper end of the housing; a shaft vertically moved along the inner surface of the housing cap while being coupled with the outer surface of the stem and connected to the lower end of the button, wherein a button is mounted in the upper end of a shaft; a housing cap for guiding the vertical movement of the shaft, for connecting the housing to the closure, and for sealing the inner space of the housing from the outside; a piston vertically moved along the inner wall of the housing while being mounted in the lower portion of the stem; a compression spring positioned between the button and the housing cap to provide restoring force to the shaft during pumping; and an opening and closing member positioned in the lower end of the inner space of the housing to open and close an introducing hole in the lower end of the housing during pumping, and characterized in that: the opening and closing member has a hollow portion whose upper end is opened and it has radial protrusions formed on the sides toward the outside, and a vertical extending portion is formed in the lower end of the stem and able to move within the hollow portion of the opening and closing member, said vertical extending portion has perpendicular minute grooves such that the inside of said hollow portion of the opening and closing member communicates with the inner space of the housing even in a state where the lower extending portion is combined with the hollow portion in order to prevent the pressure of the inside of the hollow portion from changing, and said vertical extending portion is inserted into the hollow portion of the opening and closing member and minute protrusions are formed on the inner side of the hollow portion in order to increase frictional force with respect to the vertical extending portion. a button having a discharge hole; a housing constituting the external appearance of a plump; a cloture coupled with the outer surface in the upper portion of the housing through a housing cap to mount the housing in a container; a stem having a horizontal passage communicated with the inner space of the housing and a vertical passage communicated with the horizontal passage and vertically moved while protruding from the upper end of the housing; a shaft vertically moved along the inner surface of the housing cap while being coupled with the outer surface of the stem and connected to the lower end of the button, wherein a button is mounted in the upper end of a shaft; a housing cap for guiding the vertical movement of the shaft, for connecting the housing to the closure, and for sealing the inner space of the housing from the outside; a piston vertically moved along the inner wall of the housing while being mounted in the lower portion of the stem; a compression spring positioned between the button and the housing cap to provide restoring force to the shaft during pumping; and an opening and closing member positioned in the lower end of the inner space of the housing to open and close an introducing hole in the lower end of the housing during pumping, and characterized in that: the opening and closing member has a hollow portion whose upper end is opened and it has radial protrusions formed on the sides toward the outside, and a vertical extending portion is formed in the lower end of the stem and able to move within the hollow portion of the opening and closing member, said vertical extending portion has perpendicular minute grooves such that the inside of said hollow portion of the opening and closing member communicates with the inner space of the housing even in a state where the lower extending portion is combined with the hollow portion in order to prevent the pressure of the inside of the hollow portion from changing, and said vertical extending portion is inserted into the hollow portion of the opening and closing member and minute protrusions are formed on the inner side of the hollow portion in order to increase frictional force with respect to the vertical extending portion. the opening and closing member has a hollow portion whose upper end is opened and it has radial protrusions formed on the sides toward the outside, and a vertical extending portion is formed in the lower end of the stem and able to move within the hollow portion of the opening and closing member, said vertical extending portion has perpendicular minute grooves such that the inside of said hollow portion of the opening and closing member communicates with the inner space of the housing even in a state where the lower extending portion is combined with the hollow portion in order to prevent the pressure of the inside of the hollow portion from changing, and said vertical extending portion is inserted into the hollow portion of the opening and closing member and minute protrusions are formed on the inner side of the hollow portion in order to increase frictional force with respect to the vertical extending portion.