A cab capable of shielding solar radiation comprises a pair of front pillars and a pair of vertical beams; a front window glass member mounted movably along guide rails formed along the front pillars and the vertical beams, between a closing position for closing a front window formed between the front pillars and an opening position for opening the front window accommodated between the vertical beams; a roll screen and a winding member, wherein the winding member is disposed behind the inner surface of the front window glass member positioned at the closing position and in front of the front end of the front window glass member positioned at the opening position and on the outer side of the pair of guide rails; and a holding means attached to the front pillars and configured to releasably hold the leading end of the screen.