The Election Commission is confident the Senate election will be held smoothly despite the Constitutional Court's ruling to nullify the general election on February 2.
EC secretary-general Puchong Nutrawong said that prior to the advance Senate election today, no group had come out to oppose it.
More than 2 million eligible voters have registered for advance voting.
Absentee voting will also be held today to elect 77 senatorial seats, representing 77 provinces.
The Senate election is set for next Sunday.
The Senate comprises 77 elected senators and 73 appointed senators.