"One of the patients diagnosed in (the northeastern region of) Catalonia is a pregnant woman, who showed symptoms after having travelled to Colombia," the health ministry said, adding she is one of seven cases in Spain and all are in good condition.
The woman is reportedly between 13 and 14 weeks pregnant when she showed the flu like symptoms associated with the virus.
Zika could infect hundreds of thousands of people in Spain if local mosquitoes begin to transmit the virus, scientists have warned.
Fernando Simón, the director of the health ministry's emergency alert centre, said the government was expecting to have to deal with 200 to 250 cases this year, an estimate based on an anticipated average of up to 20 cases per month.
But Frederic Bartumeus, a research professor based in Catalonia believes the problem could be far worse if the tiger mosquito (aedes albopictus), which is found in parts of Spain, begins to spread the disease.
He told The Telegraph he could imagine "hundreds of thousands of zika cases in Spain".
The World Health Organization declared a state of emergency on Monday over zika virus, which has been spreading since a massive outbreak started last spring in Brazil.
Symptoms tend to be mild, including a rash, fever and headaches. But experts have observed a potential link between pregnant mothers with the virus and their babies being born with brain damage.
Since October, Brazil has reported 404 confirmed cases of microcephaly where the baby's head is abnormally small -- up from 147 in 2014 -- plus 3,670 suspected cases.
The timing has fuelled strong suspicions that Zika is causing the birth defect.
The virus has also been linked to a potentially paralysing nerve disorder called Guillain-Barre syndrome in some patients.
There is currently no vaccine.
Spain's health ministry nevertheless sought to ease concerns, pointing out that all seven patients had caught the disease abroad.
"Up to now, the diagnosed cases of Zika virus in Spain... don't risk spreading the virus in our country as they are imported cases," it said.Spanish officials have warned that pregnant women planning to travel to affected areas should consult a doctor.