An assembly of a working vehicle and a front loader , the front loader including a pair of main frames , a pair of coupling frames , a pair of booms and a bucket and being configured to attach the booms to the working vehicle ; each main frame supporting a corresponding boom via a corresponding coupling frame and including a first frame and a second frame ; the first frame having a first support part having a first support surface that is oriented on a first virtual plane (P1) and is fixed to one portion of a vehicle body; and a second support part having a second support surface that is oriented on a different virtual plane (P2) from the first virtual plane (P1) and is fixed to another portion of the vehicle body; wherein the first and second virtual planes (P1, P2) are vertical to the left-right direction of the vehicle body ; the first frame is configured such that the first support part and the corresponding portion of the vehicle body are mutually fixed at the first support surface , and the second support part and the corresponding portion of the vehicle body are mutually fixed at the second support surface ; and the first frame further comprises a third support part : formed in a plate shape, having a front side surface arranged vertically to the front-back direction of the vehicle body, and fixed to a front upper end of the second support part ; characterized in that the first frame is further configured such that the front side surface of the third support part is located in a portion of the vehicle body different from portions which the first and second support surfaces are fixed to. the front loader including a pair of main frames , a pair of coupling frames , a pair of booms and a bucket and being configured to attach the booms to the working vehicle ; each main frame supporting a corresponding boom via a corresponding coupling frame and including a first frame and a second frame ; the first frame having a first support part having a first support surface that is oriented on a first virtual plane (P1) and is fixed to one portion of a vehicle body; and a second support part having a second support surface that is oriented on a different virtual plane (P2) from the first virtual plane (P1) and is fixed to another portion of the vehicle body; wherein the first and second virtual planes (P1, P2) are vertical to the left-right direction of the vehicle body ; the first frame is configured such that the first support part and the corresponding portion of the vehicle body are mutually fixed at the first support surface , and the second support part and the corresponding portion of the vehicle body are mutually fixed at the second support surface ; and the first frame further comprises a third support part : formed in a plate shape, having a front side surface arranged vertically to the front-back direction of the vehicle body, and fixed to a front upper end of the second support part ; formed in a plate shape, having a front side surface arranged vertically to the front-back direction of the vehicle body, and fixed to a front upper end of the second support part ; characterized in that the first frame is further configured such that the front side surface of the third support part is located in a portion of the vehicle body different from portions which the first and second support surfaces are fixed to. <EOS>