1. A wireless charging device comprising: a case part and a cover part; wherein the cover part comprises a first cover and a second cover the first cover including an upper area on which a portable electronic device is positioned for charging; wherein the case part comprises an upper housing disposed under the second cover, and a lower housing coupled to the upper housing; and at least one charging coil disposed between the upper housing and the lower housing and configured to supply electric power to the portable electronic device to be charged; whereby at least a portion of a surface of the first cover has a frictional force of a specific magnitude, and the second cover is disposed under the first cover and has an elasticity of a specific magnitude, said elasticity being such that the cover part may be pressed to the lower side of the cover part or toward the upper housing by the weight of the portable electronic device as the portable electronic device is held on the cover part; a power source part connected to the at least one charging coil; and a holding state changing part configured to change holding states of the upper housing in correspondence to an external pressure, between a stand state in which the upper housing stands while having a specific angle with respect to the lower housing, and a horizontally disposed state in which the upper housing and the lower housing are disposed in parallel, wherein the lower housing includes a seating part exposed while the upper housing is held in said stand state; wherein the holding state changing part includes a sliding part and a hinge part connected together, the sliding part being configured to move the upper housing horizontally with respect to the lower housing, and the hinge part being configured to rotate the upper housing upwards with respect to the lower housing, whereby, when switching from the horizontally disposed state to the stand state: the upper housing positioned on the lower housing may be slid from the lower housing in correspondence to an external pressure applied in a first direction, and the stand state may include a state of various angles in correspondence to an external pressure. a case part and a cover part; wherein the cover part comprises a first cover and a second cover the first cover including an upper area on which a portable electronic device is positioned for charging; wherein the case part comprises an upper housing disposed under the second cover, and a lower housing coupled to the upper housing; and at least one charging coil disposed between the upper housing and the lower housing and configured to supply electric power to the portable electronic device to be charged; whereby at least a portion of a surface of the first cover has a frictional force of a specific magnitude, and the second cover is disposed under the first cover and has an elasticity of a specific magnitude, said elasticity being such that the cover part may be pressed to the lower side of the cover part or toward the upper housing by the weight of the portable electronic device as the portable electronic device is held on the cover part; a power source part connected to the at least one charging coil; and a holding state changing part configured to change holding states of the upper housing in correspondence to an external pressure, between a stand state in which the upper housing stands while having a specific angle with respect to the lower housing, and a horizontally disposed state in which the upper housing and the lower housing are disposed in parallel, wherein the lower housing includes a seating part exposed while the upper housing is held in said stand state; wherein the holding state changing part includes a sliding part and a hinge part connected together, the sliding part being configured to move the upper housing horizontally with respect to the lower housing, and the hinge part being configured to rotate the upper housing upwards with respect to the lower housing, whereby, when switching from the horizontally disposed state to the stand state: the upper housing positioned on the lower housing may be slid from the lower housing in correspondence to an external pressure applied in a first direction, and the stand state may include a state of various angles in correspondence to an external pressure.