Provided is a method of joining members having different thermal expansion coefficients, capable of joining them at a temperature lower than the melting point of Ag to obtain a joining layer having excellent durability to a thermal cycle. First Ag particles 3 having an average particle diameter of 50 nm or less and an Ag foil 4 or metal foil 4 having a smaller modulus of longitudinal elasticity than that of Ag are placed between two types of members 1 and 2 at least one of which has a lower thermal expansion coefficient than that of Ag, heated to join the members 1 and 2. A wax material 3, which is a powder mixture containing first Ag particles having an average particle diameter of 50 nm or less and second Ag particles or particles of a metal (having a modulus of longitudinal elasticity than that of Ag) having an average particle diameter of 20 μm or more and being contained in a volume fraction of 10 to 40% relative to a total volume of the powder mixture, is placed between the two types of members 1 and 2, heated to join the members 1 and 2. The metal foil 4 and the particles of a metal have an Ag coating layer on a surface thereof. The first member 1 is formed of one type of material selected from the group consisting of Si, SiC, Al2O3, AlN and Si3N4 and the second member is formed of Al or Cu.