PURPOSE: To lock lining markers in an upright housing attitude at a timing when the lining markers exit just before a planting device reaches the highest position.

CONSTITUTION: Locking means 16 for holding lining markers 13 in an upright housing attitude and freely releasing locking in order to change the upright housing attitude to a lying action attitude consists of working members 19 which are connected through wires 17 to the lining markers 13, rotated in the locking direction through a pressing member 31 equipped with a rise and fall link mechanism 8 with linking to rise of a planting device 12 and turned in unlocking direction with linking to fall of the planting device 12, checking members 20 which are engaged with the working members 19 to automatically lock the working members and to unlock by manual operation and a rise and fall link mechanism 8 which makes the pressing members 31 which rotate the working members 19 in the locking direction relatively adjustable in position based on the working members 19 and is attached to a traveling machine body 3.