An electronic circuit module includes (i) a semiconductor integrated circuit component which is a transistor integrated circuit formed on a semiconductor substrate, (ii) a passive element component constituting a peripheral circuit of the semiconductor integrated circuit component, and (iii) first and second circuit substrates each of which has a component mounting surface on which at least one of the semiconductor integrated circuit component and the passive element component. The respective component mounting surfaces of the first and second circuit substrate face one another. The first circuit substrate functions as one outer wall of a housing, where the electronic circuit module contacts an external circuit substrate on which the electronic circuit module is mounted. The second circuit substrate functions as the other outer wall of the housing of the module.