In a flow control apparatus, a fluid pressure is introduced from downstream of a metering orifice to a rear room (32) of a spool (20) while a relief valve in the spool (20) is assembled in advance. A front section (41a) of a relief valve sub-assembly (40) is press fitted to a hole (21) provided on the spool and is opening to rear room (32) of the spool so that a receiving room of a valve body in a relief valve casing (41) communicates to a bypass path (13). A communicating path (41b) provided in a rod communicates to the rear room of the spool through outside of the relief valve subassembly (40). The relief valve casing (41) is received in a receiving hole (21) provided in the spool (20) and a cylindrical room between the relief valve casing and the receiving room is used as a part of a communicating path.