To provide an expansion apparatus capable of reliably producing an effect of reducing refrigerant flow noise and a refrigerant cycle of a vehicle air conditioner using the expansion apparatus. In an expansion apparatus 1 in which a valve body 41 of a refrigerant flow rate adjustment mechanism 40 is accommodated in a valve chest 5 of a main body 2 to which a refrigerant is led, a first narrow portion 4 is provided between a lead-in passage 3 and the valve chest 5, and a second narrow portion 6 having a flow passage area smaller than that of the first narrow portion 4 is provided between the valve chest 5 and a lead-out passage 7, the valve chest 5 is formed so as to have a space S around the valve body 41 and the first narrow portion 4 is formed so as to face the space S around the valve body 41, so that the refrigerant led to the valve chest 5 from the first narrow portion 4 flows toward the second narrow portion 6 through the space S around the valve body 41 without passing through a coil spring 43.
