A work vehicle comprising: a front loader detachably attached to a vehicle body; and an attaching mechanism for attaching the front loader to the vehicle body, the attaching mechanism including an engaged member provided in the vehicle body, an engaging member provided in the front loader to be engageable with an engaged member, and a support member provided in the front loader so as to support the engaged member; wherein the attaching member attaches the front loader to the vehicle body by engagement of the engaging member with the engaged member; and the engaging member engages the engaged member while the engaged member is supported by the support member, wherein the front loader includes a pair of left and right booms that support an implement, and a pair of left and right side frames that support base end portions of the booms to be pivotable about a pivot axis extending along the vehicle body left-right direction and that is detachably attached to the vehicle body; a pair of left and right attaching frames are provided in the vehicle body for attaching the front loader to the vehicle body; the engaging member and the support member are provided in each of the side frames; and the engaged member is provided in each of the attaching frames, wherein each of the side frames is provided with a pin; each of the attaching frames is provided with a recess; and when a bucket is dumped and the pin on the side frame side is fitted in the recess on the attaching frame side with the front loader being supported on a stand, the engaged member will be located at an inlet portion of the support member to come into contact with the engaging member, whereby the engaging member will be pivoted from the engaging position to the non-engaging position, characterized in that when the side frame is brought to a vertical posture, the engaged member being fitted into a recess of the support member to be received and supported by a receiving portion of the support member; and the engaging member comes into engagement with the engaged member, while the engaged member being received and supported by the receiving portion of the support member. a front loader detachably attached to a vehicle body; and an attaching mechanism for attaching the front loader to the vehicle body, the attaching mechanism including an engaged member provided in the vehicle body, an engaging member provided in the front loader to be engageable with an engaged member, and a support member provided in the front loader so as to support the engaged member; wherein the attaching member attaches the front loader to the vehicle body by engagement of the engaging member with the engaged member; and the engaging member engages the engaged member while the engaged member is supported by the support member, wherein the front loader includes a pair of left and right booms that support an implement, and a pair of left and right side frames that support base end portions of the booms to be pivotable about a pivot axis extending along the vehicle body left-right direction and that is detachably attached to the vehicle body; a pair of left and right attaching frames are provided in the vehicle body for attaching the front loader to the vehicle body; the engaging member and the support member are provided in each of the side frames; and the engaged member is provided in each of the attaching frames, wherein each of the side frames is provided with a pin; each of the attaching frames is provided with a recess; and when a bucket is dumped and the pin on the side frame side is fitted in the recess on the attaching frame side with the front loader being supported on a stand, the engaged member will be located at an inlet portion of the support member to come into contact with the engaging member, whereby the engaging member will be pivoted from the engaging position to the non-engaging position, characterized in that when the side frame is brought to a vertical posture, the engaged member being fitted into a recess of the support member to be received and supported by a receiving portion of the support member; and the engaging member comes into engagement with the engaged member, while the engaged member being received and supported by the receiving portion of the support member.