A safety belt take-up device provided with a double sensing type emergency-lock mechanism comprises webbing draw acceleration sensing means, vehicle acceleration sensing means, first transmission means and lock means. The webbing draw acceleration sensing means may shift from a first position to a second position when a webbing is drawn out at an acceleration greater than a predetermined value. The vehicle acceleration sensing means may shift from a first position to a second position when the vehicle acceleration has exceeded a predetermined value. The first transmission means is connectible to a take-up spindle along with the shift from the first position to the second position of the webbing draw acceleration sensing means and/or the vehicle acceleration sensing means and adapted to shift from a first position to a second position due to the webbing draw-out force. The lock means may prevent the draw-out of the webbing when the first transmission means has shifted to its second position.