In the display device DD, the plurality of input pads PI of the connection circuit board FPCB which are connected to the main circuit board MPCB, include the plurality of first input pads PI1 defining the input pad row PI-A and the second input pad PI2 having the maximum width greater than that of the first input pad PI1 along the first direction DR1 that is a direction of the input pad row PI-A. Also, the second input pad PI2 includes the plurality of vertical arrangement pads PI-V and the power pad PI-P which is disposed adjacent to the plurality of vertical arrangement pads PI-V along the second direction DR2 that is an extension direction (e.g., major dimension direction) of the second input pad PI2. As the second input pad PI2 includes the power pad PI-P and the plurality of vertical arrangement pads PI-V which function as the inspection pad, the number of pads disposed on the input pad row PI-A of the connection circuit board FPCB along a row direction may be reduced to increase the gap between the pads disposed within the input pad row PI-A and thus reduce or effectively prevent a limitation such as short-circuit between the pads. Also, although the third length d3 of the power pad PI-P along the second direction DR2 is less than the first length d1 of the first input pad PI1 since the power pad PI-P is aligned with the plurality of vertical arrangement pads PI-V, as the third width W3 of the power pad PI-P along the first direction DR1 is greater than the first width W1 of the first input pad PI1, the planar area of the power pad PI-P may be secured to be equal to or greater than that of the first input pad PI1. Thus, a connection characteristic of the power pad PI-P may be secured. With the connection characteristic of the power pad PI-P secured, the display device DD including the connection circuit board FPCB connected to the display panel DP may have improved reliability.