A logic device includes first and second logic blocks and a connection block. Each of the first and second logic blocks configured to perform at least one function, the first logic blocks connected to first connection lines and the second logic blocks connected to second connection lines. The connection block electrically connected to the first and second logic blocks via the first connection lines and the second connection lines, respectively. The connection block including connection cells configured to select one of multiple connection configurations between the first connection lines and the second connection lines based on a desired function.