A mouse device includes a mouse body and a scrolling wheel. The mouse body has a front curved surface, a rear curved surface and a bottom. The bevel and a rear edge of the front curved surface are respectively connected to the bottom and the rear curved surface. The included angle of the front curved surface and the bottom is between 45 and 70 degrees. The scrolling wheel is disposed on the bevel. When operating the mouse device, the user uses an index finger and a portion connecting the index finger and the palm to form an arch atop of the front curved surface and the rear curved surface, thus the mouse body is largely under the index finger. The user can tilt the mouse body for the first scrolling wheel to contact with a working surface and scroll a monitor's screen frame.