A movable discharge device for use in a particle/bulk material storage silo, the movable discharge device being configured to travel along a groove provided at a lower portion of the storage silo and discharge particle/bulk material in the storage silo downward through the groove, the movable discharge device comprising: a travel body configured to travel along the groove; a scrape-out unit configured to move integrally with the travel body and including a blade configured to rotate above the groove to rake the particle/bulk material in the storage silo and scrape out the particle/bulk material to the groove; wherein: the blade is one of two blades provided so as to be symmetrical about a rotational center of the blades; the movable discharge device being characterized by comprising a groove covering mechanism configured to cover a predetermined region of the groove within a rotation trajectory region of the blade; the groove covering mechanism includes groove covering plate sets configured to respectively cover conveying-direction front and rear portions of the groove within the rotation trajectory region of the blades; and each of the groove covering plate sets is constituted by a plurality of groove covering plates (53, 55, 56, 57) that cover the predetermined region of the groove, so that the covered area of the groove can be changed by changing the number of groove covering plate arranged so that the opening area of the groove can be easily adjusted depending on the type of particle/bulk material, the discharge amount, and the like. a travel body configured to travel along the groove; a scrape-out unit configured to move integrally with the travel body and including a blade configured to rotate above the groove to rake the particle/bulk material in the storage silo and scrape out the particle/bulk material to the groove; wherein: the blade is one of two blades provided so as to be symmetrical about a rotational center of the blades; the movable discharge device being characterized by comprising a groove covering mechanism configured to cover a predetermined region of the groove within a rotation trajectory region of the blade; the groove covering mechanism includes groove covering plate sets configured to respectively cover conveying-direction front and rear portions of the groove within the rotation trajectory region of the blades; and each of the groove covering plate sets is constituted by a plurality of groove covering plates (53, 55, 56, 57) that cover the predetermined region of the groove, so that the covered area of the groove can be changed by changing the number of groove covering plate arranged so that the opening area of the groove can be easily adjusted depending on the type of particle/bulk material, the discharge amount, and the like. the blade is one of two blades provided so as to be symmetrical about a rotational center of the blades; the movable discharge device being characterized by comprising a groove covering mechanism configured to cover a predetermined region of the groove within a rotation trajectory region of the blade; the groove covering mechanism includes groove covering plate sets configured to respectively cover conveying-direction front and rear portions of the groove within the rotation trajectory region of the blades; and each of the groove covering plate sets is constituted by a plurality of groove covering plates (53, 55, 56, 57) that cover the predetermined region of the groove, so that the covered area of the groove can be changed by changing the number of groove covering plate arranged so that the opening area of the groove can be easily adjusted depending on the type of particle/bulk material, the discharge amount, and the like.