An outside widening method of a tubular knitted fabric for forming a widening stitch on an outer side of an end in a longitudinal direction of a needle bed of a tubular knitted fabric in a process of knitting the tubular knitted fabric including a first side knitted fabric portion held on one of front and back needle beds and a second side knitted fabric portion held on the other needle bed using a flat knitting machine having at least a pair of front and back needle beds and in which stitches are transferrable between the front and back needle beds wherein the method is characterised by: when assuming a direction from a position scheduled to form a widening stitch towards the tubular knitted fabric is inward and an opposite direction is outward in a movement direction of a yarn feeder along the longitudinal direction of the needle bed, process A of, immediately after knitting a new stitch row α following in a wale direction of the first side knitted fabric portion, forming a first pick-up stitch (4, 14) to become the widening stitch on an empty needle, which is positioned on an outward side of a stitch (2, 11) at an end of the second side knitted fabric portion on a side same as a stitch at a termination of the stitch row α, of knitting needles of the other needle bed on which the other side knitted fabric portion is held while moving the yarn feeder outward; process B of forming a second pick-up stitch (5, 17) to become the widening stitch on an empty needle, which is positioned on an outward side of the first pick-up stitch (4, 14), of knitting needles of the other needle bed while moving the yarn feeder inward; process C of knitting a new stitch row β following in a wale direction of the second side knitted fabric portion after forming the second pick-up stitch (5, 17); and process D of knitting a new stitch row γ following in the wale direction of the stitch row α and the first pick-up stitch (4, 14), and knitting a new stitch row δ following in the wale direction of the stitch row β and the second pick-up stitch (5, 17); wherein after forming a stitch at a starting end of the stitch row β in the process C and before forming a new stitch (8, 18) following in the wale direction of the first pick-up stitch (4, 14) in the process D, the first pick-up stitch (4, 14) is transferred to an empty needle, which is positioned on an outward side of a stitch (3, 15) at a termination of the stitch row α, of knitting needles of the one needle bed. when assuming a direction from a position scheduled to form a widening stitch towards the tubular knitted fabric is inward and an opposite direction is outward in a movement direction of a yarn feeder along the longitudinal direction of the needle bed, process A of, immediately after knitting a new stitch row α following in a wale direction of the first side knitted fabric portion, forming a first pick-up stitch (4, 14) to become the widening stitch on an empty needle, which is positioned on an outward side of a stitch (2, 11) at an end of the second side knitted fabric portion on a side same as a stitch at a termination of the stitch row α, of knitting needles of the other needle bed on which the other side knitted fabric portion is held while moving the yarn feeder outward; process B of forming a second pick-up stitch (5, 17) to become the widening stitch on an empty needle, which is positioned on an outward side of the first pick-up stitch (4, 14), of knitting needles of the other needle bed while moving the yarn feeder inward; process C of knitting a new stitch row β following in a wale direction of the second side knitted fabric portion after forming the second pick-up stitch (5, 17); and process D of knitting a new stitch row γ following in the wale direction of the stitch row α and the first pick-up stitch (4, 14), and knitting a new stitch row δ following in the wale direction of the stitch row β and the second pick-up stitch (5, 17); wherein after forming a stitch at a starting end of the stitch row β in the process C and before forming a new stitch (8, 18) following in the wale direction of the first pick-up stitch (4, 14) in the process D, the first pick-up stitch (4, 14) is transferred to an empty needle, which is positioned on an outward side of a stitch (3, 15) at a termination of the stitch row α, of knitting needles of the one needle bed.