A heat medium circulation device comprising: a first heat medium circuit provided with a heating unit configured to heat a heat medium; a first pump provided in the first heat medium circuit to forcibly flow the heat medium from upstream to downstream of the first heat medium circuit; a second heat medium circuit which is provided with a heat utilizing load using the heat of the heat medium and is connected to the first heat medium circuit; a second pump provided in the second heat medium circuit to forcibly flow the heat medium from upstream to downstream of the second heat medium circuit; and a heat medium circulation control unit configured to synchronously activate the first pump and the second pump to circulate the heat medium between the first heat medium circuit and the second heat medium circuit in a case of using the heat of the heat medium by using the heat utilizing load, wherein a connector is provided between the first heat medium circuit and the second heat medium circuit to connect both circuits; the connector includes: a body with an internal hollow formed by a cylindrical peripheral wall; a first inlet port which is formed in the body peripheral wall to introduce the heat medium from the first heat medium circuit to an inside of the body; a first outlet port which is formed in a position for receiving the heat medium, which is introduced from the first inlet port formed in the body peripheral wall, to deliver the heat medium from the inside of the body to the second heat medium circuit; a second inlet port which is formed in the body peripheral wall to introduce the heat medium from the second heat medium circuit into the inside of the body; and a second outlet port which is formed in a position for receiving the heat medium, which is introduced from the second inlet port formed in the body peripheral wall, to deliver the heat medium from the inside of the body to the first heat medium circuit; and the heat medium circulation control unit includes an anti-freezing control unit configured to perform an anti-freezing treatment for preventing the heat medium in the first heat medium circuit from freezing by activating the first pump; characterized in that the anti-freezing control unit is configured to deactivate the second pump during the anti-freezing treatment so that the second pump is.in a stopped state. a first heat medium circuit provided with a heating unit configured to heat a heat medium; a first pump provided in the first heat medium circuit to forcibly flow the heat medium from upstream to downstream of the first heat medium circuit; a second heat medium circuit which is provided with a heat utilizing load using the heat of the heat medium and is connected to the first heat medium circuit; a second pump provided in the second heat medium circuit to forcibly flow the heat medium from upstream to downstream of the second heat medium circuit; and a heat medium circulation control unit configured to synchronously activate the first pump and the second pump to circulate the heat medium between the first heat medium circuit and the second heat medium circuit in a case of using the heat of the heat medium by using the heat utilizing load, wherein a connector is provided between the first heat medium circuit and the second heat medium circuit to connect both circuits; the connector includes: a body with an internal hollow formed by a cylindrical peripheral wall; a first inlet port which is formed in the body peripheral wall to introduce the heat medium from the first heat medium circuit to an inside of the body; a first outlet port which is formed in a position for receiving the heat medium, which is introduced from the first inlet port formed in the body peripheral wall, to deliver the heat medium from the inside of the body to the second heat medium circuit; a second inlet port which is formed in the body peripheral wall to introduce the heat medium from the second heat medium circuit into the inside of the body; and a second outlet port which is formed in a position for receiving the heat medium, which is introduced from the second inlet port formed in the body peripheral wall, to deliver the heat medium from the inside of the body to the first heat medium circuit; and the heat medium circulation control unit includes an anti-freezing control unit configured to perform an anti-freezing treatment for preventing the heat medium in the first heat medium circuit from freezing by activating the first pump; characterized in that the anti-freezing control unit is configured to deactivate the second pump during the anti-freezing treatment so that the second pump is.in a stopped state.