A high frequency module used as a unit circuit making up a phased array antenna, in which the module may be reduced in size with reduction in cost. A high frequency module 10 includes a dielectric substrate 1 having both surfaces metallized. The dielectric substrate has a first metallized layer 2 and a second metallized layer 3 formed on both surfaces and has a low noise amplifier and the phase shifter IC 9 mounted on the metallized layer 2 on one surface. The high frequency module 10 also includes a low noise transistor 7 and a distributed constant circuit 12, formed on the one surface of the dielectric substrate 1 to form the low noise amplifier together, and an input terminal 5, an output terminal 6 and power supply terminals 15A to 15D formed by leading out the metallized layer 2 on the one surface to the opposite side surface of the dielectric substrate 1 in such a manner as to maintain insulation from the metallized layer 3 on the opposite side surface. The high frequency module further includes a metal cap 13 provided for covering at least a circuit component loading surface of the dielectric substrate 1.