A magnetic field detection apparatus includes a magnetoresistive effect element and a coil. The coil includes first and second tier parts opposed to each other in a first axis direction, with the magnetoresistive dal element interposed therebetween. The coil is configured to be supplied with a current and thereby configured to generate an induction magnetic field to be applied to the magnetoresistive effect element in a second axis direction. The first tier part includes first conductors extending in a third axis direction, arranged in the second axis direction and coupled in parallel to each other. The second tier part includes a second conductor or second conductors extending in the third axis direction, the second conductors being arranged in the second axis direction and coupled in parallel to each other. The first conductor each have a width smaller than a width of the second conductor or each of the second conductors.