Fuel tank having a sub-tank provided on the inside of the fuel tank body

A fuel tank comprising:

• a tank body including a bottom wall, a lateral wall and an upper wall, the tank body storing fuel in an interior surrounded by the bottom wall, the lateral wall and the upper wall;
• and
• a sub-tank storing a part of the fuel, the sub-tank including a wall portion, an opening portion and a post portion,
• the wall portion standing on the bottom wall and extending toward the upper wall,
• the opening portion being provided in the wall portion and being a portion in which the fuel flows,
• the post portion being provided integrally with the wall portion, being extended along a height direction of the wall portion from the bottom wall and being joined to the bottom wall and the upper wall,
• the post portion includes a fragile portion where an area of a section orthogonal to an extending direction of the post portion is smaller than a section area of parts of the post portion other than the fragile portion, and
• when a direction from the bottom wall toward the upper wall is an upward direction and a direction from the upper wall toward the bottom wall is a downward direction, the post portion includes a first rib at a portion below the fragile portion and a second rib at a portion above the fragile portion, the first rib extending in an up-down direction, the second rib extending in the up-down direction.