A joining method for joining together a first member in which fiber material is mixed into a first resin, and a second member that includes at least a second resin, the joining method using a stirring member including a pin member and a shoulder portion, the shoulder portion having a a generally circular cylindrical shape that has a void into which the pin member is inserted so as to surround the pin member and the pin member and the shoulder portion that form the stirring member each being configured to rotate together as a single unit around an axis (Xr), as well as being able to move relative to one another in the direction of the axis (Xr), and the joining method comprising: abutting the first member and the second member together; softening or melting the first resin of the first member and the second resin of the second member that are adjacent to abutting surfaces of the first member and the second member; stirring a joint forming portion formed by the softened or melted first resin of the first member, the softened or melted second resin of the second member, and the fiber material included in the softened or melted first resin of the first member, in a direction inclined with respect to the abutting surfaces; wherein when stirring and hardening the joint forming portion, the joint forming portion is stirred in a direction orthogonal to the abutting surfaces; when stirring the joint forming portion in the direction orthogonal to the abutting surfaces, the stirring member is inserted into the joint forming portion, the inserted stirring member is moved in the direction orthogonal to the abutting surfaces, and the joint forming portion is stirred in the direction orthogonal to the abutting surfaces so that fibers of the first member included in the joint forming portion are oriented in the direction orthogonal to the abutting surfaces; and when stirring the joint forming portion in the direction orthogonal to the abutting surfaces, the pin member is moved in the direction of the axis (Xr) one of towards and away from the abutting surfaces while the shoulder portion is moved in the direction of the axis (Xr) the other of towards and away from the abutting surfaces while the pin member and the shoulder portion of the stirring member are rotated together as a unit around the axis (Xr); the joining method further comprising: stopping rotation of the pin member and the shoulder portion and moving the pin member in the direction of the axis (Xr) the other of towards and away from the abutting surfaces while moving the shoulder portion in the direction of the axis (Xr) the one of towards and away from the abutting surfaces: removing the stirring member from the joint forming portion; and hardening the joint forming portion. abutting the first member and the second member together; softening or melting the first resin of the first member and the second resin of the second member that are adjacent to abutting surfaces of the first member and the second member; stirring a joint forming portion formed by the softened or melted first resin of the first member, the softened or melted second resin of the second member, and the fiber material included in the softened or melted first resin of the first member, in a direction inclined with respect to the abutting surfaces; wherein when stirring and hardening the joint forming portion, the joint forming portion is stirred in a direction orthogonal to the abutting surfaces; when stirring the joint forming portion in the direction orthogonal to the abutting surfaces, the stirring member is inserted into the joint forming portion, the inserted stirring member is moved in the direction orthogonal to the abutting surfaces, and the joint forming portion is stirred in the direction orthogonal to the abutting surfaces so that fibers of the first member included in the joint forming portion are oriented in the direction orthogonal to the abutting surfaces; and when stirring the joint forming portion in the direction orthogonal to the abutting surfaces, the pin member is moved in the direction of the axis (Xr) one of towards and away from the abutting surfaces while the shoulder portion is moved in the direction of the axis (Xr) the other of towards and away from the abutting surfaces while the pin member and the shoulder portion of the stirring member are rotated together as a unit around the axis (Xr); the joining method further comprising: stopping rotation of the pin member and the shoulder portion and moving the pin member in the direction of the axis (Xr) the other of towards and away from the abutting surfaces while moving the shoulder portion in the direction of the axis (Xr) the one of towards and away from the abutting surfaces: removing the stirring member from the joint forming portion; and hardening the joint forming portion. stopping rotation of the pin member and the shoulder portion and moving the pin member in the direction of the axis (Xr) the other of towards and away from the abutting surfaces while moving the shoulder portion in the direction of the axis (Xr) the one of towards and away from the abutting surfaces: removing the stirring member from the joint forming portion; and hardening the joint forming portion.