[Object] To significantly increased the convenience in suctioning dust on a mop with use of a negative pressure of an electric vacuum cleaner.[Solution] A hose coupling device 10 includes a connecting pipe 14, a branch pipe 15, a ball valve 40. The connecting pipe 14 has openings, one of the openings configured as a first inlet 31 and another one of the openings configured as an outlet 33 communicating with the one of the openings. The branch pipe 15 continues from a lateral surface of the connecting pipe 14 and has an opening configured as a second inlet 32. The ball valve 40 is arranged in a valve box 35 at which the connecting pipe 14 and the branch pipe 15 communicate such that the ball valve 40 is rotatable about a rotation axis corresponding to an axis of the branch pipe 15 while the ball valve 40 remains in contact with an inner wall of the valve box 35. The ball valve 40 includes a first sidewall 41, a second sidewall 42, a third sidewall 43 facing the branch pipe 15, a through hole 45, and a communicating groove 46 extending from the third sidewall 43 to the second sidewall 42. The ball valve 40 is configured to rotate about the rotation axis between a first communicating position to connect the first inlet 31 to the outlet 33 via the through hole 46 and a second communicating position to connect the second inlet 32 to the outlet 33 via the communicating groove 46.